Uplink feedback methods for operating with a large number of carriers

ABSTRACT

A wireless transmit/receive unit (WTRU) may receive one or more physical downlink shared channel (PDSCH) transmissions and each PDSCH transmission may be associated with downlink control information (DCI) and a group of PDSCH transmissions. Further, the WTRU may determine a first group or a second group based on an indication received in DCI associated with at least one of the PDSCH transmissions. Then, the WTRU may generate hybrid automatic repeat request (HARQ)-acknowledgment (ACK) feedback for data received in one or more PDSCH transmissions associated with the determined group. Moreover, the WTRU may transmit the HARQ-ACK feedback. In an example, the DCI which includes the indication may schedule a plurality of PDSCH transmissions included in the determined group. In another example, the DCI which includes the indication may further include a first codepoint mapped to the first group or a second codepoint mapped to the second group.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/340,933, filed Jun. 7, 2021, which is a continuation of U.S. patentapplication Ser. No. 16/827,022, filed Mar. 23, 2020, which issued asU.S. Pat. No. 11,032,053 on Jun. 8, 2021, which is a continuation ofU.S. patent application Ser. No. 15/546,559 filed Jul. 26, 2017, whichissued as U.S. Pat. No. 10,601,567 on Mar. 24, 2020, which is the U.S.National Stage, under 35 U.S.C. § 371, of International Application No.PCT/US2016/015413 filed Jan. 28, 2016, which claims the benefit of U.S.Provisional Application No. 62/250,890, filed Nov. 4, 2015, U.S.Provisional Application No. 62/214,552, filed Sep. 4, 2015, U.S.Provisional Application No. 62/166,523, filed May 26, 2015, U.S.Provisional Application No. 62/161,057, filed May 13, 2015, U.S.Provisional Application No. 62/144,835, filed Apr. 8, 2015, and U.S.Provisional Application No. 62/108,849, filed Jan. 28, 2015, the entirecontents of which are hereby incorporated by reference herein.

BACKGROUND

Carrier aggregation for Long Term Evolution (LTE) was introduced in3^(rd) Generation Partnership Project (3GPP) Release 10. This featureallows a wireless transmit/receive unit (WTRU) to transmit and receiveon more than one carrier simultaneously, resulting in an increase of itspeak data rate over the air interface. The maximum number of carriersthat may be aggregated is five (5), for a maximum bandwidth of 100megahertz (MHz).

Transmission of data in the downlink in LTE may be performed using thephysical downlink shared channel (PDSCH). This physical channel supportshybrid automatic repeat request (HARQ) transmission, in which thereceiver (at the WTRU) may combine successive transmissions of atransport block to increase the probability of successful decoding ateach retransmission. The WTRU may report, for a given reception attemptof a transport block, that the reception has succeeded with anacknowledgement (ACK) or has not succeeded with a negativeacknowledgement (NACK). In some cases, the WTRU may also report that itdid not detect that a transport block was transmitted, such as indiscontinuous transmission (DTX).

SUMMARY

A method and apparatus for uplink feedback for operating with a largenumber of carriers are disclosed herein. A method in a wirelesstransmit/receive unit (WTRU) includes receiving a downlink controlinformation (DCI), wherein the DCI schedules a physical downlink sharedchannel (PDSCH) transmission and the DCI includes an indication,determining whether a hybrid automatic repeat request (HARQ)acknowledgment (ACK)/negative acknowledgement (NACK) (A/N) report isexpected for the PDSCH transmission based on the indication in the DCI,and receiving a HARQ A/N report on a condition that one is expected forthe PDSCH transmission.

Further examples include a solution for reducing HARQ-ACK payload,increasing physical uplink control channel (PUCCH) payload, increasinguplink control information (UCI) payload in a physical uplink sharedchannel (PUSCH) and determining the resource or sub-resource used forthe transmission of a feedback group, or a combination of feedbackgroups, based on a combination of downlink control signaling that isassociated with any PDSCH and of an index or order associated with thisfeedback group.

Additional examples include the dynamic scheduling of UCI on a PUCCH,and an index for each downlink assignment, to enable a dynamic codebookand feedback compression. In an example, the WTRU may make adetermination of order of the information bits in the codebook. The WTRUmay make a selection of a codebook permutation to optimize decodingperformance. A further example includes a codebook indicator. Further, aspecific group of carriers to select may be determined based on whichcarriers assignments are received for. In addition, the codebook may bedetermined using one or more methods. Also, an A/N resource indicator(ARI) may be used for the determination of a final assignment. Further,multiple channel state information (CSI) reports may be transmitted in asubframe using one or more methods. For example, the WTRU may beconfigured with a maximum payload for each PUCCH resource that can beused for the transmission of HARQ-ACK, periodic CSI reports and/orscheduling request (SR) in a subframe.

In an example, a WTRU may receive a plurality of transport blocks over aset of a plurality of configured carriers, generate HARQ-ACK feedbackfor the plurality of transport blocks and determine a number of HARQ-ACKfeedback bits to use for the HARQ-ACK feedback. Further, the WTRU mayapply, to the HARQ-ACK feedback bits, Reed-Muller coding on a conditionthat the number of HARQ-ACK feedback bits is less than or equal to athreshold. The WTRU may then transmit the encoded HARQ-ACK feedbackbits.

In addition, the WTRU may append cyclic redundancy check (CRC) bits ontothe HARQ-ACK feedback bits on a condition that the number of HARQ-ACKfeedback bits is greater than a threshold. Also, the WTRU may applyconvolutional coding to the HARQ-ACK feedback bits and the CRC bits on acondition that the number of HARQ-ACK feedback bits is greater than athreshold. The WTRU may then transmit the encoded HARQ-ACK feedback bitsand CRC bits.

Further, the WTRU may determine the number of HARQ-ACK feedback bits touse for the HARQ-ACK feedback based on a plurality of downlinkassignments for carriers in the set of configured carriers. The set ofconfigured carriers may include more than five configured carriers.

In another example, a WTRU may receive a plurality of transport blocksover a set of a plurality of configured carriers and generate HARQ-ACKfeedback and CSI feedback for the plurality of transport blocks. TheWTRU may then generate a feedback message that includes a number ofHARQ-ACK feedback bits to use for the HARQ-ACK feedback and a number ofCSI feedback bits to use for the CSI feedback. The WTRU may thendetermine a PUCCH format based on the number of HARQ-ACK feedback bitsand the number of CSI feedback bits. In addition, the WTRU may thentransmit the feedback message using the determined PUCCH format.

Further, the WTRU may determine the number of HARQ-ACK feedback bits touse for the HARQ-ACK feedback, the number of CSI feedback bits to usefor the CSI feedback, or both, based on a plurality of downlinkassignments for carriers in the set of configured carriers. In anexample, the WTRU may select from four PUCCH formats.

In another example, a WTRU may receive a plurality of transport blocksover a plurality of configured carriers. The WTRU may generate HARQ-ACKfeedback for the plurality of transport blocks, CSI feedback for atleast one of the plurality of configured carriers, and a CRC. Further,the WTRU may generate a feedback message that includes a number ofHARQ-ACK feedback bits for the HARQ-ACK feedback, a number of CSIfeedback bits for the CSI feedback, and a number of CRC bits for theCRC. The WTRU may then determine a power to be used for a PUCCHtransmission based on the number of HARQ-ACK feedback bits, the numberof CSI feedback bits, and the number of CRC bits. Moreover, the WTRU maytransmit the feedback message in the PUCCH transmission at thedetermined power.

In an example, the number of CRC bits may be based on the number ofHARQ-ACK feedback bits and the number of CSI feedback bits. In a furtherexample, the WTRU may generate a SR. Also, the feedback message mayfurther include a number of SR bits for the SR. Moreover, the number ofCRC bits may be based on the number of HARQ-ACK feedback bits, thenumber of CSI feedback bits and the number of SR bits.

In another example, the number of HARQ-ACK feedback bits for theHARQ-ACK feedback or the number of CSI feedback bits for the CSIfeedback may be determined based on at least one of a number oftransport blocks or a number of carriers in the plurality of configuredcarriers. Also, the number of HARQ-ACK feedback bits for the HARQ-ACKfeedback or the number of CSI feedback bits for the CSI feedback may bedetermined based on a number of subframes over which the transportblocks are received. Further, the WTRU may transmit the feedback messagein the PUCCH transmission at the determined power in a subframe.

In a further example, a WTRU may receive one or more PDSCH transmissionsand each PDSCH transmission may be associated with DCI and a group ofPDSCH transmissions. Further, the WTRU may determine a first group or asecond group based on an indication received in DCI associated with atleast one of the PDSCH transmissions. Then, the WTRU may generateHARQ-ACK feedback for data received in one or more PDSCH transmissionsassociated with the determined group. Moreover, the WTRU may transmitthe HARQ-ACK feedback.

In an example, the DCI which includes the indication may schedule aplurality of PDSCH transmissions included in the determined group. Inanother example, the DCI which includes the indication may furtherinclude a first codepoint mapped to the first group or a secondcodepoint mapped to the second group. In an additional example, the DCIwhich includes the indication may further includes an uplink controlinformation (UCI) request.

Also, all of the received one or more PDSCH transmissions may bereceived over the same carrier, in an example. In addition, the firstgroup may be a first feedback group and the second group may be a secondfeedback group.

Moreover, the determination may be further based on a DCI formatassociated with the DCI which includes the indication. In anotherexample, the DCI format may schedule the one or more PDSCH transmissionsassociated with the determined group. In a further example, the data mayinclude user data. Further, a specific radio network temporaryidentifier (RNTI) may indicate the DCI which includes the indication, inan example.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 10 is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 is a diagram of an example of possible resource element (RE)mapping for extended Physical Uplink Control Channel (PUCCH) designutilizing two contiguous resource blocks (RBs);

FIG. 3 is a diagram of an example selection process for a PUCCH formatbased on the size and type of feedback;

FIG. 4 is a diagram of an example of a hybrid automatic repeat request(HARQ) acknowledgment/negative acknowledgement (A/N) codebookdetermination; and

FIG. 5 is a diagram of an example selection process for channel codingand inclusion of cyclic redundancy check (CRC) based on the number offeedback bits to be transmitted.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (VVTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the VVTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the VVTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a Node-B, an eNode B,a Home Node B, a Home eNode B, a site controller, an access point (AP),a wireless router, and the like. While the base stations 114 a, 114 bare each depicted as a single element, it will be appreciated that thebase stations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple-output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (Vol P) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (10), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 10 is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the core network 106.

The RAN 104 may include eNode-Bs 140 a, 140 b, 140 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 140 a, 140 b, 140c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 140 a, 140 b, 140 c may implement MIMO technology. Thus,the eNode-B 140 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 140 a, 140 b, 140 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 10 , theeNode-Bs 140 a, 140 b, 140 c may communicate with one another over an X2interface.

The core network 106 shown in FIG. 10 may include a mobility managemententity gateway (MME) 142, a serving gateway 144, and a packet datanetwork (PDN) gateway 146. While each of the foregoing elements aredepicted as part of the core network 106, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MME 142 may be connected to each of the eNode-Bs 140 a, 140 b, 140 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 142 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 142 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 144 may be connected to each of the eNode Bs 140 a,140 b, 140 c in the RAN 104 via the S1 interface. The serving gateway144 may generally route and forward user data packets to/from the WTRUs102 a, 102 b, 102 c. The serving gateway 144 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 102 a,102 b, 102 c, managing and storing contexts of the WTRUs 102 a, 102 b,102 c, and the like.

The serving gateway 144 may also be connected to the PDN gateway 146,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The core network 106 may facilitate communications with other networks.For example, the core network 106 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 106 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 106 and the PSTN 108. In addition, the corenetwork 106 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

Carrier aggregation for LTE was introduced in 3^(rd) GenerationPartnership Project (3GPP) Release 10. This feature allows a WTRU totransmit and receive on more than one carrier simultaneously, resultingin an increase of its peak data rate over the air interface. In anunmodified form of carrier aggregation, the maximum number of carriersthat may be aggregated is five (5), for a maximum bandwidth of 100megahertz (MHz).

Transmission of data in the downlink in LTE may be performed using thephysical downlink shared channel (PDSCH). This physical channel supportshybrid automatic repeat request (HARQ) transmission, in which thereceiver (at the WTRU) may combine successive transmissions of atransport block to increase the probability of successful decoding ateach retransmission. The WTRU may report, for a given reception attemptof a transport block, that the reception has succeeded with anacknowledgement (ACK) or has not succeeded with a negativeacknowledgement (NACK). In some cases the WTRU may also report that itdid not detect that a transport block was transmitted, such as indiscontinuous transmission (DTX). Such reporting may collectively bereferred to as “HARQ-ACK feedback” herein. The result of a specificreception attempt of a transport block (ACK or NACK, or in certainsolutions ACK, NACK or DTX) may be referred to as a “HARQ A/N report”herein.

When carrier aggregation is configured, up to 2 transport blocks may bereceived per carrier (or serving cell) and subframe on the PDSCHchannel. In Frequency Division Duplex (FDD) mode, the WTRU may report 1bit of HARQ-ACK feedback separately for each transport block where ACKis transmitted if the transport block was received successfully and NACKis transmitted otherwise. In Time Division Duplex (TDD) mode, in someconfigurations, the WTRU may report 1 bit of HARQ-ACK for each pair oftransport blocks received in the same carrier and subframe (for example,spatially multiplexed) or 1 bit of HARQ-ACK for a set of transportblocks received in the same carrier and in a set of subframes, where ACKis transmitted if all transport blocks of a pair or set are receivedsuccessfully and NACK is transmitted otherwise. Such a scheme, where theWTRU reports ACK on a condition that all of a set of more than onetransport block is successfully received, and NACK otherwise, may bereferred to as “A/N bundling”. A/N bundling may be performed fortransport blocks spatially multiplexed (spatial bundling), for transportblocks received in different subframes (time bundling) or for transportblocks received in different carriers or cells (frequency bundling).

In both modes, there is a fixed timing relationship between thereception of a transport block and the transmission of a HARQ-ACK bitdependent on the success or failure of the reception of this transportblock. More specifically, in FDD mode a HARQ-ACK bit corresponding to atransport block received in subframe n may be transmitted in subframen+4. In TDD mode, the timing relationship may depend on the subframeconfiguration and on the index of the subframe in which the transportblock is received.

Transmission of HARQ-ACK bits in a subframe may be performed on either aPhysical Uplink Control Channel (PUCCH) or a Physical Uplink SharedChannel (PUSCH) physical channel. PUCCH may be used when no PUSCHtransmission is available in a subframe, or when the WTRU is configuredto simultaneously transmit PUCCH and PUSCH.

PUCCH may occupy a single physical resource block (PRB) in each timeslot of a subframe and may be transmitted according to one of a set ofpossible formats. When more than 4 HARQ-ACK bits need to be transmittedon PUCCH in a single subframe, the WTRU may need to be configured to usePUCCH format 3. PUCCH format 3 may be described as a Discrete FourierTransform-Spread-Orthogonal Frequency Division Multiplexing (DFT-S-OFDM)transmission where each quadrature phase shift keying (QPSK)-modulatedsymbol occupies a single sub-carrier and is spread in the time domainusing one of a set of orthogonal cover codes. In PUCCH format 3, eachQPSK-modulated symbol may be spread over one time slot such that 48coded bits may be accommodated in a subframe (2 time slots times 12sub-carriers times 2 bits per symbol). Up to 10 HARQ-ACK bits (in FDDmode) or 20 HARQ-ACK bits (in TDD mode) may be multiplexed with up to 1scheduling request (SR) bit to be encoded into those 48 coded bits.

Within a cell, up to 4 WTRUs may transmit mutually orthogonal PUCCHformat 3 in the same resource block. However, the maximum number ofWTRUs that may be configured to use the same resource block may besmaller when inter-cell interference is significant.

When HARQ-ACK bits in a subframe need to be transmitted over PUSCH, thecorresponding modulated symbols may be mapped onto resource elementsoccupying a portion (or all) subcarriers in 4 time symbols adjacent tothe time symbols used for the transmission of demodulation referencesignals (DM-RSs) in the subframe. The number of resource may bedetermined based on the size of PUSCH allocation and a parameterconfigured such that the amount of energy available to HARQ-ACK issufficient to ensure that an error performance target is met.

To enhance the carrier aggregation feature, it has been proposed toenable aggregation of up to 32 carriers. This enhancement may bechallenging from the perspective of providing HARQ-ACK feedback sincereusing the same solutions as in the legacy system may now require thetransmission of up to 64 HARQ-ACK bits (for FDD mode) or 128 HARQ-ACKbits (for TDD mode). This may create the following concerns. First, themaximum number of coded bits available in a PUCCH transmission (48) maybe lower than the number of HARQ-ACK (and SR) information bitsdetermined using the legacy solutions. Second, the amount of energy usedfor HARQ-ACK (and SR) transmission in PUSCH may become insufficient toensure acceptable error performance.

It has also been proposed that the WTRU may be configured with PUCCH onone or more Secondary Cells (SCells). In such a case, the WTRU may needto determine whether to transmit some or all of the uplink controlinformation (UCI) using a single transmission and, if so, whether to usea PUCCH transmission on a Primary Cell (PCell) (or Primary SCell(PSCell) if for the Secondary Cell Group (CG) (SCG)), a PUSCHtransmission on a cell of the master cell group (MCG) (if available andUCI is associated with the MCG) or a PUSCH transmission on a cell of theSCG (if available and UCI is associated with the SCG).

Methods and solutions are disclosed herein for reducing HARQ-ACKpayload, including the following. Conditional generation of a HARQ A/Nreport may be based on the satisfaction of one or more conditions, suchas, for example, conditions regarding the Modulation and Coding Scheme(MCS) and/or reported Channel Quality Indicator (CQI). Also, selectivepartial bundling may be used where groups of transport blocks (TBs) forwhich bundling is applied are selected on a subframe basis to minimizeunnecessary retransmissions. Further, the down-selection ofacknowledgement reports may be used.

Methods and solutions are disclosed herein for increasing PUCCH payload,including the following. For example, methods and solutions aredisclosed herein for the use of higher-order modulation, possibly on asubset of sub-carriers to implement unequal error protection. Also,methods and solutions are disclosed herein for the use of more than 1resource block (RB), using new a DM-RS design allowing multiplexing withlegacy formats while maintaining low cubic metric (CM). In addition,methods and solutions are disclosed herein for the use of spatialmultiplexing, where the number of information bits on each layer may bedynamically selected. Further, the modulation symbols may be spread overfewer resource elements (REs) than in an unmodified approach, where thenumber of symbols may be dynamically selected.

Methods and solutions are disclosed herein for the efficient use ofresources, including the following. Codebook properties may bedynamically determined, based on, for instance, downlink controlsignaling. Also, a codebook permutation may be selected to optimizedecoding performance. In addition, multiple feedback groups may betransmitted and processed separately or jointly, and a feedback groupindicator may be used to facilitate decoding. Further, resourceselection and mapping, a power setting function of the PUCCH and/or thedynamic scheduling of UCI on PUCCH may be used. Also, an indication ofindex and/or counter for each downlink assignment may be used to enablea dynamic codebook as well as feedback compression.

Methods and solutions are disclosed herein for increasing UCI payload inthe PUSCH, including the following. Modified transport block processingmay be used when the number/proportion of REs in PUSCH exceeds athreshold.

Methods and solutions are disclosed herein for resource selection incase of multiple types of transmission in multiple cells. Also, methodsand solutions are disclosed herein for the transmission of multipleperiodic CSI reports in a subframe.

Methods and solutions are disclosed herein for a codebook determination,which may use an Acknowledgment/Negative Acknowledgement (A/N) resourceindicator (ARI) for the determination of the final assignment, and thetransmission of multiple CSI reports.

The following solutions address the problem of limited payload (orrange) for the transmission of HARQ-ACK by allowing a reduction of thenumber of information bits used for HARQ-ACK.

In some solutions, the number of information bits generated for HARQ-ACKmay be reduced by restricting the generation of a HARQ A/N report (orbit) for a given transport block only when at least one condition issatisfied. The at least one condition may be defined such thatunnecessary retransmissions of a transport block by the network areminimized. Generally this may be achieved if the at least one conditionis such that the A/N report is generated only when the probability ofsuccessful decoding is significant.

In legacy LTE systems, the WTRU may typically generate a HARQ A/N reportwhen it receives a transmission on PDSCH and/or when it receives adownlink control information (DCI) that activates or deactivates aconfigured uplink grant or a configured downlink assignment.

In one method, the WTRU may perform further determination whengenerating a HARQ A/N report. The WTRU may generate a HARQ A/N reportfor a transmission associated with a specific carrier (or associatedwith a specific serving cell) of the WTRU's configuration, according toat least one of the following.

The WTRU may receive a DCI, such as a DCI characterized by at least oneof the following: a DCI type, an indication inside the DCI, a RadioNetwork Temporary Identifier (RNTI) used for the successful decoding ofthe DCI, a search space associated with the received DCI, a location ofthe DCI in the search space, an aggregation level of the DCI, other DCIcontents, or a combination thereof.

For DCI type, the WTRU may determine whether or not a HARQ A/N report isexpected for a transmission as a function of the type (or format) of DCIassociated with the transmission. For example, the WTRU may receive aDCI of a specific type (or format) and determine that a HARQ A/N reportmay not be generated. Such an association may be based on the DCI formatitself. For example, the DCI may also carry the scheduling informationfor the concerned transmission. Such an association may be based ontiming, such as for example, a DCI of a specific type (or format)received in the same subframe as DCI that schedules one or moretransmissions in the concerned subframe. Such a type may include a DCItype that may possibly be used to provide “hints” in support of WTRUprocessing of downlink control signaling. Such DCI may indicate that notransmission is applicable for the concerned carrier in the givensubframe. Alternatively, such DCI may indicate that the WTRU is notexpected to generate HARQ A/N feedback for one or more carriers.Possibly, such DCI may indicate, for example, using a codepoint, aspecific format and/or combination of carriers for which a HARQ A/Nreport is expected for the concerned interval (for example, a subframe).Further examples of such DCI are described herein. Similar to legacysystems, the WTRU may be required to generate HARQ A/N report for a DCIthat activates or deactivates a configured grant and/or a configureddownlink allocation, while other DCI formats may require additionalrules to determine whether or not to generate a HARQ A/N report.

For indication inside the DCI, the WTRU may determine whether or not aHARQ A/N report is expected for a transmission as a function of thecontents of a DCI associated with the transmission. For example, theWTRU may receive a DCI, for example, that schedules a PDSCHtransmission. Such DCI may include an indication. The WTRU may determinefrom such indication whether or not a HARQ A/N report is expected forthe concerned PDSCH transmission. Possibly, such DCI may indicate, forexample, using a codepoint, a specific format and/or combination ofcarriers for which a HARQ A/N report is expected for the concernedinterval (for example, subframe). The indication may consist of thevalue of a field included in the payload of the DCI, or of the value ofa field used to mask a subset or all bits of the cyclic redundancy check(CRC). The field may consist, for instance, of a downlink assignmentindex (DAI) field, or of a dedicated field (HARQ A/N reportingindicator).

For RNTI used for the successful decoding of the DCI, the WTRU maydetermine whether or not a HARQ A/N report is expected for atransmission as a function of the RNTI used to successfully decode a DCIassociated with the transmission. For example, the WTRU may beconfigured with a plurality of RNTIs. The WTRU may be configured suchthat the successful decoding of a DCI when using a given RNTI mayindicate that a HARQ A/N report is not required for the associatedtransmission (or conversely, that a HARQ A/N report is required).

For search space associated with the received DCI, the WTRU maydetermine whether or not a HARQ A/N report is expected for atransmission as a function of the search space of the DCI associatedwith the transmission. For example, the WTRU may be expected to generateHARQ A/N report for a transmission associated with a DCI received in theCommon Search Space (CSS) but possibly not for a DCI received in theWTRU-specific Search Space (or UE-specific Search Space (UESS)) and/orthe WTRU may apply additional rules in the latter case. For example, theWTRU may be configured with a plurality of UESSs (or similar, forexample, the UESS may be portioned) where reception of a DCI in aspecific UESS (or portion thereof) may indicate that a HARQ A/N reportis not expected while such may be expected for a different UESS (orportion thereof).

For location of the DCI in the search space, the WTRU may determinewhether or not a HARQ A/N report is expected for a transmission as afunction of a control channel element (CCE) of a DCI associated with thetransmission. For example, such CCE may be the first CCE for thereceived DCI. For example, CCEs may be organized using a numerologicalsequence (for example, where the first CCE of a SS is #0, the second CCEcorresponds to #2, and the like) such that the WTRU may determine that aHARQ A/N report may be expected when the first CCE of a DCI coincidewith a specific CCE in the SS (for example, for even indices) but maynot be expected for another CCE in the SS (for example, for oddindices).

For aggregation level of the DCI (for example, number of CCEs such as 1,2, 4 or 8 CCEs), the WTRU may determine whether or not a HARQ A/N reportis expected for a transmission as a function of the aggregation level(AL) of a DCI associated with the transmission. For example, the WTRUmay be expected to generate a HARQ A/N report for a transmissionassociated with AL of 4 or more, while it may not be required otherwise.

For other DCI contents, for example, scheduling information and/ortransmission characteristics may be used (as further described herein).In one method, the WTRU may use any of the above methods to determine ifthe successfully decoded DCI includes a UCI (or HARQ feedback only)request, such as described herein.

The WTRU may determine that the transmission is characterized accordingto at least one of the following: an identity of the associated HARQprocess, a redundancy version, an initial transmission or retransmissionfor the concerned HARQ process, a type of scheduling for thetransmission, timing associated with the transmission, schedulingparameters, a simultaneous downlink transmission and/or aggregation sizeof UCI, or a combination thereof.

For identity of the associated HARQ process, the WTRU may determinewhether or not a HARQ A/N report is expected for a transmission as afunction of the identity of the HARQ process associated with thetransmission (or indicated in the DCI). For example, the WTRU may beconfigured such that it may not be expected to generate a HARQ A/Nreport for a subset of HARQ processes, while it may generate HARQ A/Nreport for other processes. For example, the WTRU may determine that aHARQ A/N report is always expected for a process configured with asemi-persistent assignment.

For redundancy version (e.g., 0,2,3,1), the WTRU may determine whetheror not a HARQ A/N report is expected for a transmission as a function ofthe redundancy version (RV) associated with the transmission. Forexample, the WTRU may generate a HARQ A/N report for RV=2, 3, 1 but notfor RV=0.

For initial transmission or retransmission for the concerned HARQprocess, the WTRU may determine whether or not a HARQ A/N report isexpected for a transmission as a function of whether the transmission isthe initial transmission for the HARQ process or not. For example, theWTRU may determine that it is expected to generate a HARQ A/N report forHARQ retransmissions only.

For type of scheduling for the transmission, the WTRU may determinewhether or not a HARQ A/N report is expected for a transmission as afunction of whether dynamic scheduling information was received for thetransmission (for example, DCI on a Physical Downlink Control Channel(PDCCH) that provided transmission parameters) or whether thetransmission is received using a configured assignment For example, theWTRU may determine that a HARQ A/N report may not be required for atransmission dynamically scheduled (for example, it may always berequired for semi-persistent assignments), possibly making furtherdetermination in combination with other methods described herein.

For timing associated with the transmission (or with the transmission ofthe associated UCI), the WTRU may determine whether or not a HARQ A/Nreport is expected for a transmission as a function of the transmissiontime interval (TTI) (or subframe, or slot) associated with the downlinktransmission. For example, the WTRU may be configured such that it maynot be required to generate a HARQ A/N report for one or more subframes(for example, even frames) within a frame.

For scheduling parameters (for example, size of TBs, MCS, and the like),possibly in relation to another metric, such as channel quality, theWTRU may determine whether or not a HARQ A/N report is expected for atransmission as a function of the parameters associated with thetransmission. For example, the WTRU may determine that a HARQ A/N reportis required for a TBS larger than a specific value, and otherwise it maynot be required. Similarly, MCS may be used as the determination factor.For example, the WTRU may determine that a HARQ A/N report may beoptional if expected BLER is higher than a threshold. The WTRU may use acombination of the last reported CSI and one or more properties of thedownlink transmission such as the MCS larger than a threshold functionof a CQI and the transmission rank larger than rank indicator (RI).

For simultaneous downlink transmission(s) and/or aggregation size ofUCI, the WTRU may determine whether or not a HARQ A/N report is expectedfor a transmission as a function of the number of payload bits, totalsum for all transport blocks or any other aggregated metric associatedwith the time interval when the transmission satisfies a specificcondition, e.g., is larger than X. The WTRU may perform a similardetermination as a function of the aggregated size of the UCI, forexample, the sum of the HARQ A/N bits expected according to the legacybehavior may exceed a certain value X bits.

A combination of the examples discussed may be used. For example, theWTRU may determine that it is configured such that HARQ A/N report forone (or more) specific HARQ process(es) is generated (possibly at least)upon reception of an explicit feedback request such as reception of aDCI(UCI) described herein, otherwise the WTRU may not generate a HARQA/N report for the concerned process(es); such behavior may be combinedwith additional rules such that the WTRU may generate HARQ A/N reportunder other circumstances. For example, the WTRU may generate HARQ A/Nreport starting from the xth retransmission for the concerned HARQprocess(es) and/or when the WTRU receives dynamic scheduling for uplinkresources for UCI reporting such as described herein.

Methods described herein may be applicable as a function of the physicalchannel used for reporting. The WTRU may determine whether or not it mayperform the above determination or if the legacy behavior for generationof a HARQ A/N report, as a function of the type of uplink transmission,may be used to convey the UCI. For example, the WTRU may use the legacybehavior when it determines that HARQ A/N reports may be transmittedusing one (or more) PUSCH transmission(s). The WTRU may determine thatsome HARQ A/N reports may be optional when it determines that HARQ A/Nreports may be transmitted using one (or more) PUCCH transmission(s).The WTRU may perform such determination as a function of the timing ofconcerned the uplink transmission.

Methods described herein may be applicable as a function of the carrierassociated with the transmission. The WTRU may determine whether or notit may perform the above determination or if the legacy behavior forgeneration of a HARQ A/N report, as a function the type of carrier, maybe associated with the downlink transmission. For example, the WTRU mayuse a first method for carrier(s) in a licensed band while it may beused a second method for carrier(s) in an unlicensed band. For example,the WTRU may generate a HARQ A/N report (or more generally, a UCIreport) for HARQ processes (and/or for CSI) associated with anunlicensed band (for example, for LTE License-Assisted Access (LAA))when it successfully receives a DCI that includes a UCI (or HARQfeedback only) request (such as described herein). In which case, forexample, the WTRU may report the status of the concerned HARQprocess(es) where such status may, for example, be determined at (andcorrespond to) the time of the reception of such request. Otherwise theWTRU may not necessarily generate the concerned UCI feedback (forexample, other rules may apply). For example, the WTRU may not generateHARQ A/N report for every received transmission.

For any of the examples discussed herein, such transmission may be atleast one of the following: a PDSCH and DCI of a specific type. Thetransmission may be a PDSCH transmission. The transmission may be asidelink. The transmission may be a direct WTRU-to-WTRU transmission,for example, a physical sidelink shared channel (PSSCH) (for example,for data), a physical sidelink control channel (PSCCH) (for control),and/or a physical sidelink discovery channel (PSDCH) (for example, fordiscovery).

The transmission may be a DCI that modifies a semi-persistent downlinkassignment or a semi-persistent uplink grant. The transmission may be aDCI(UCI), for example, that includes a UCI request and/or dynamic UCIscheduling information, for example, as described herein. The DCI may beany other DCI, for example, for which any of the above methods may beapplied.

For any of the examples discussed herein, such transmission may beassociated with a serving cell, which serving cell may be at least oneof the following: type of serving cell of the WTRU's configuration, cellconfiguration, group of cells, state of the cell, and quality of thecell.

In an example, the serving cell may be the type of serving cell of theWTRU's configuration. For example, the cell may be a Secondary Cell(such as a SCell) of the WTRU's configuration such that conditional HARQA/N reporting is applied to such transmission for such cell. Forexample, the WTRU may not apply conditional HARQ A/N reporting to anysuch transmission for a Primary Cell (such as a PCell) of the WTRU'sconfiguration for a WTRU configured with carrier aggregation or for aWTRU configured with dual connectivity. For example, the WTRU may notapply conditional HARQ A/N reporting to any such transmission for aspecial cell of a secondary cell group (such as a PSCell) for a WTRUconfigured with dual connectivity.

In another example, the serving cell may be configured in a cellconfiguration. For example, the cell may be configured (such as by radioresource control (RRC), or by medium access control (MAC)) such thatconditional HARQ A/N reporting is applied to such transmission for suchcell.

Also, in an example, the serving cell may be part of a group of cells.For example, the cell may be part of a specific group of cells such thatconditional HARQ A/N reporting is applied to such transmission for suchcells such as a “HARQ A/N group.” Such group may correspond to asecondary cell group (for example, a service continuity gateway (SCG))for a WTRU configured with dual connectivity. Such group may correspondto a secondary timing advance group (for example, a secondary TimingAdvance Group (sTAG)) for a WTRU configured with carrier aggregation.

In an additional example, the serving cell may be associated with astate of the cell. For example, the cell may be associated with a statefor the purpose of controlling whether or not conditional HARQ A/Nreporting is applied. The WTRU may modify such a state based on a numberof events, for example, reception of L1 signaling or reception of L2/MACcontrol signaling that indicates a change in the state for the cell. Forexample, the cell may be in the deactivated state such that conditionalHARQ A/N reporting is applied to uplink control signaling associatedwith the cell.

In a further example, the quality of the serving cell may be used. Forexample, the quality of the cell may be based on WTRU-measurements. Forexample, the WTRU may determine that the quality of the cell is below(or above) a certain threshold and, until the WTRU determines that thequality changes sufficiently significantly and possibly also for asufficient amount of time, determine whether or not it may applycondition HARQ A/N reporting for such transmission for the cell. TheWTRU may perform such determination only for cells for which it reportsa measurement, for example, a channel quality indicator (CQI). The WTRUmay perform such determination when it performs the transmission of suchmeasurement for the concerned cell.

Additional control information may be located inside the uplinktransmission that contains a UCI report. In one method, the WTRU maysignal inside the uplink transmission whether or not non-legacy handlingof HARQ A/N bits has been applied by, for example, transmitting one bitto indicate whether conditional HARQ A/N has been applied to the uplinkcontrol signaling, or it may append a CRC. For example, the WTRU mayperform at least one of the following: concatenate one bit (one bit flagindication is added to the transmission); concatenate CRC (for example,a 3-bit CRC may be added to the transmission, whereby different methodsmay be associated with different CRC calculations); and use differentresource/property of PUCCH.

In one method, the WTRU may use any of the above to associate priorityto a HARQ A/N report for such transmission. The WTRU may additionallyhandle the information bit associated with the HARQ A/N report accordingto at least one of the following: the WTRU may drop the information bit,the WTRU may set the value of the information bit to a specific value,the WTRU may bundle the information bit with other information bits, theWTRU may encode the information bit with less protection, and the WTRUmay transmit the information bit using a different physical layerchannel.

Where the WTRU may drop the information bit, the WTRU may not, forexample, transmit any HARQ A/N for a low priority transmission. In suchcase, the WTRU may select a different (possibly smaller) format if theresulting total number of HARQ A/N bits to transmit is suitable for theselected format. Alternatively, the WTRU may perform the uplinktransmission of HARQ A/N signaling, if any, such that the eNode-B mayinterpret the absence of the concerned HARQ A/N bit as a NACK.

Where the WTRU may set the value of the information bit to a specificvalue (such as to NACK), the WTRU may use coding for the HARQ A/N bitssuch that no energy is used for HARQ NACK transmissions and the eNode-Bmay interpret the absence of HARQ A/N as a NACK.

Where the WTRU may bundle the information bit with other informationbits (such as of similar priority), the WTRU may bundle, for example, aplurality of HARQ A/N information bits based on an activation state ofthe SCell associated with the transmission for which HARQ feedback wasgenerated. For example, feedback for carriers of similar priority may bebundled together. Possibly, only for carriers associated with uplinkcontrol information of low priority.

Where the WTRU may encode the information bit with less protection, forexample, the WTRU may do so in cases where unequal error protection isapplied to transmission of information bits.

Where the WTRU may transmit the information bit using a differentphysical layer channel, the WTRU may transmit the information bits usinga different physical layer channel than was used for transmission ofbits of higher priority.

The solutions described in the above may also be used to determinewhether the WTRU transmits HARQ A/N over a specific resource or channel.For example, in case the WTRU may determine that transmission over PUCCHor over a specific PUCCH resource takes place only if at least one HARQA/N bit is transmitted based on one of the solutions.

In some examples discussed herein, selective partial bundling may beused. In some examples, the number of information bits generated forHARQ-ACK may be reduced by applying bundling for a subset of groups oftransport blocks that may be dynamically selected to minimize theresulting number of unnecessary retransmissions.

More generally, a WTRU may apply a first solution for generatingHARQ-ACK information bits on a first subset of groups of transportblocks, and a second solution on a second subset of transport blocks,where the first and second subsets of transport blocks are selectedbased on at least one criterion that may change dynamically. Forexample, the criterion may be that the number of correctly receivedtransport blocks for which the WTRU does not indicate positiveacknowledgment is minimized for a given number of HARQ-ACK informationbits. The WTRU may generate additional HARQ-ACK information bits toindicate which groups belong to the first and second subsets, using forinstance a combinatorial index.

An example for generating HARQ-ACK information bits on a group oftransport blocks may include at least one of the following: no bundling,full bundling, and partial bundling. For no bundling, one bit may begenerated for each transport block, where a first value (“ACK” or 1) isgenerated on a condition that the transport block was correctly receivedand a second value (“NACK” or 0) is generated on a condition that thetransport block was not correctly received or not received at all. Forfull bundling, one bit may be generated for all transport blocks, wherea first value (“ACK” or 1) is generated on a condition that alltransport blocks were correctly received, and a second value (“NACK” or0) otherwise. For partial bundling, one bit may be generated for each ofa number of subsets of transport blocks of the group, where for eachsubset of transport blocks, a first value (“ACK” or 1) is generated on acondition that all transport blocks of the subset were correctlyreceived, and a second value (“NACK” or 0) otherwise.

In the above, a subset and/or a group of transport blocks may be, forexample, defined as transport blocks that may be received from a certainserving cell (or subset thereof), a certain subframe (or subsetthereof), or combination thereof. The groups may be explicitlyconfigured by higher layers, or implicitly derived from theconfiguration (for example, the group size may be set to a fixed valueand groups may be defined from the order of configured serving cells ofthe configuration).

For example, a WTRU may be configured with 32 serving cells in FDD andreceive up to 64 transport blocks in a subframe. One may define 8 groupsof 8 transport blocks, each of which may correspond to the transportblocks that may be received from a set of 4 serving cells. For 2 of the8 groups, HARQ-ACK information bits may be generated according to the“no bundling” solution while for the 6 remaining groups, HARQ-ACKinformation may be generated according to the “full bundling” solution,resulting in 16 bits plus 6 bits for all groups. In addition, 5information bits may be generated to represent a combinatorial index of28 possible combinations of 2 out of 8 groups for which the “nobundling” solution is utilized in this subframe. To select which 2 outof 8 groups the “no bundling” solution is used on, the WTRU maydetermine, for each group, the number of successfully received transportblocks with “NACK” generated if “full bundling” may be used. The WTRUmay select the 2 groups that have the largest number of suchsuccessfully received transport blocks. For example, in a subframe thenumber of successfully received transport blocks may be as follows: 8for groups 1, 4 and 8; 5 for group 2; 4 for group 3; 2 for groups 5, 6;and 0 for group 7. In this case, the WTRU may select groups 2 and 3 forthe “no bundling” solution and all other groups use “full bundling.”

The selection of the groups for which a given bundling solution is usedmay be based on at least one of the following criteria. The selection ofthe groups may be based on the minimization of the number of correctlyreceived transport blocks for which the WTRU does not indicate apositive acknowledgment in the subframe, as described herein. Also, theselection of the groups may be based on the presence or number ofcorrectly received transport blocks for which the WTRU may not indicatea positive acknowledgment in a set of previous subframes for each group.In addition, the selection of the groups may be based on the number oftimes “ACK” was not reported for a successfully received transport blockin a group. For example, the WTRU may use the “no bundling” solution forthe group for which “NACK” may be reported otherwise and that has thelargest value of this number, or for which this number may go above athreshold. Further, the selection of the groups may be based on anindication from physical layer or higher signaling of the bundlingsolution to be applied for a certain group. Such an indication may becontained in a field of PDCCH/evolved-PDCCH (E-PDCCH) containing adownlink (DL) assignment for a serving cell of the group, or in aPDCCH/E-PDCCH containing information about DL assignments in thesubframe. This may allow the network to override selection of groups bythe WTRU; whether the WTRU received a DL assignment from a specificserving cell of a group. Also, the selection of the groups may be basedon a property of one of the PDSCH transmissions of the group. Further,the selection of the groups may be based on the DCI format used forscheduling a PDSCH transmission of a group.

In examples disclosed herein, when a bundling solution is used across agroup of serving cells, the WTRU may determine if a DL assignment wasmissed in a serving cell from an indication in a PDCCH/E-PDCCHcontaining a DL assignment for another serving cell of the group. Suchindication may include a number of DL assignments that have beentransmitted in the group in this subframe. The WTRU may determine that aDL assignment was missed if the total number of correctly received DLassignments for the group in the subframe is lower that the indicatednumber, and accordingly report “nack” for the group.

In some examples, an indication of an index of cells or TBs that areACKed may be used. Further, in some examples, a WTRU may be configuredby higher layers to only use the PUCCH A/N (ACK/NACK) resources toreport ACKs. In such an example, the lack of a feedback by the WTRU maybe implied to represent a NACK at the eNode-B. TB and HARQ process maybe used interchangeably.

In a PUCCH format that enables reporting of multiple transport blockHARQ A/N bits (possibly from multiple cells), there may be apre-determined location within a bit string for each possible TB HARQA/N report. A WTRU may leave blank (or set to a pre-configured value)any bits that represent TB HARQ A/N for which a NACK may otherwise betransmitted.

In another example, there may be pre-configured locations within the bitstring where a set of TB HARQ A/N reports may be located. Such a set ofbit locations may be used to report subsets of ACKs for multiple TBs.For example, the HARQ A/N bit string reported in a PUCCH may be composedof sets of x bits each. Each set of x bits may be used to report HARQA/N for n TBs. In this example, the WTRU may be pre-configured (possiblysemi-statically) with a meaning for all the possible 2{circumflex over( )}x codepoints of the set of bits, where each codepoint may identify adifferent subset of TBs for which ACK may be assumed at the eNode-B. Asa simple numerical example, the bit string reported in a PUCCH may becomposed of 5 sets of 2 bits each. Each set of 2 bits may be used toreport ACK for any of 3 TB. For example, the codepoint ‘00’ may indicateno ACKs for any of the three TB, ‘01’ may indicate ACK for a first TB,‘10’ may indicate ACK for a second TB and ‘11’ may indicate ACK for athird TB. The meaning of each codepoint may be set semi-statically bythe eNode-B and may also indicate a group of TBs being ACKed (forexample, a codepoint may indicate that a first and a second TB are ACK).

In another example, there may not be pre-determined locations within thebit string for each TB HARQ A/N report. In such an example, there may beno need to reserve a spot within the bit string for TB HARQ A/N reportsthat are not indicating ACK. This may enable a greater number ofpossible TB HARQ A/N reports on average, given that capacity may not bewasted for TB HARQ A/N reports of NACK TBs.

In the case where pre-determined (and/or pre-configured) locationswithin a bit string of HARQ A/N reports are not used for each TB HARQA/N, the WTRU may indicate to the eNode-B the TB for which an ACK istransmitted. A WTRU may be provided with a unique identifier (possibly abit string) for each TB from all possible cells. The WTRU may reportback the identifier as an ACK within a PUCCH. For example, for the casewhere a WTRU may have up to 64 TBS transmitted within a subframe, theWTRU may be provided with an identifier for each TB made up of 6 bits.In such a case, the HARQ A/N report may simply be for the WTRU toinclude the 6-bit strings of any TB for which an ACK is transmitted. Inone example, the TB identifier may be provided when a WTRU is scheduledwith a transport block. In another example, the WTRU may determine theTB identifier as a function of an identifier of the cell transmittingthe TB (such as the cell identity (ID)) and a HARQ process ID.

In some examples presented herein, a WTRU may have multiple ACKs totransmit in a PUCCH resource. For solutions where each TB HARQ A/N isnot configured with a specific bit location in the HARQ A/N bit string,there may be situations where more ACKs are required to be transmittedin a PUCCH instance than the PUCCH capacity allows. In such a situation,the WTRU may down-select the TBs for which ACK is to be fed back in anyPUCCH instance. Any TB for which an ACK is not transmitted may beassumed to be a NACK at the eNode-B, possibly erroneously so.

The WTRU may indicate to the eNode-B that a PUCCH feedback does notinclude all the ACKs and down-selection was used by the WTRU. In anotherexample, the WTRU may include an indication along with any ACKtransmission to inform the eNode-B whether the ACK for that TB isrelative to the most recently transmitted PDSCH or to a previousversion. For example, the WTRU may only be able to transmit an ACK aftera second retransmission, when in reality it was ACKed after the firstretransmission. Indicating to the WTRU whether the ACK occurred for aprevious retransmission and/or also possibly indicating for whatretransmission the ACK occurred may enable the eNode-B with linkadaptation.

The down-selection of ACKs to transmit may be done autonomously by theWTRU following some pre-configured rules. The WTRU may determine thesubset of ACKs to transmit by at least one of: a priority list and asemi-statically configured set of rules.

The priority list may be pre-configured by the eNode-B and may bedetermined as a function of the TBs and/or SCells transmitting the TB.The WTRU may rank the ACKed TB and transmit ACK feedback for the firstTB, assuming the PUCCH has capacity to transmit n ACKS in any instance.The priority ranking may be determined by the WTRU as a function of thecontent of the PDSCH. For example, PDSCH used for control planetransmissions (such as RRC reconfiguration messages) may have higher ACKreporting priority than that of PDSCH used for user plane transmissions.The priority ranking may be dependent on the type of scheduling used forthe PDSCH. For example, cross-carrier scheduled PDSCH may havehigher/lower priority than self-scheduled PDSCH. Or semi-persistentlyscheduled PDSCH may have higher/lower priority than single scheduledPDSCH.

A semi-statically configured set of rules may enable the WTRU todetermine the TBs for which ACK may be transmitted in a PUCCH instanceup to the allowed ACK capacity in any one instance. For example, reportACKs for ACKed processes who may have had the highest number ofretransmissions. For example, the WTRU may order the TB ACK reportingpriority in terms of number of retransmissions per HARQ process andfeedback ACK for the n processes with highest number of retransmissions.For example, report ACKs for ACKed processes whose ACK reports werepreviously skipped. These may possibly be ordered by how many times anACK report was skipped for a process (such as the most skips leading tohighest ranking). For example, report ACKs for ACKed TBs withhighest/lowest data rate, and/or highest/lowest MCS, and/orhighest/lowest number of PRBs and/or, highest/lowest RI. For example,report ACKS for ACKed TBs transmitted with/without spatial multiplexing.The above rules may be used in any combination and the order that therules may be followed may be pre-configured. For example, a first rulemay be to report ACKs for ACKed processes whose ACKs were previouslyskipped. If fewer than n processes qualify, the PUCCH feedback may befurther filled with ACKs for processes that fulfill another rule (suchas processes with the highest number of retransmissions).

The priority lists and/or sets of rules may be semi-staticallyconfigured and may also depend on the timing of the PDSCH and/or PUCCH.There may be subsets of subframes such that in a first subset ofsubframes a first set of rules is used to down-select ACK feedback andin a second subset of subframes a second set of rules is used todown-select ACK feedback.

In a given subframe or group of subframes, the WTRU may determine amethod for the generation of HARQ-ACK information according to at leastone of the following: no bundling, wherein HARQ-ACK may includeconcatenated HARQ A/N reports in a pre-determined order; fixed bundlingof HARQ A/N reports for determined subsets of transport blocks (such asin spatial, frequency and/or time domain); conditional HARQ A/N reportgeneration as described herein; selective partial bundling as describedherein; and down-selection of ACK transmissions as described herein.

The selection of a method for the generation of HARQ-ACK to apply in aparticular subframe, and possibly of parameters thereof, may bedetermined according to at least one of the following: payload ofHARQ-ACK information bits, maximum payload accommodated by the PUCCHformat, maximum payload accommodated by the PUSCH transmission, and anindication from a physical layer, MAC, or RRC signaling.

Payload of HARQ-ACK information bits may be used to determine a methodto apply in a particular subframe. The payload may be determined foreither: the number of received transport blocks concerned by theHARQ-ACK transmission (based on received DL assignments) or the maximumnumber of transport blocks that may be received and concerned by theHARQ-ACK transmission (such as based on the maximum possible number ofreceived DL assignments and maximum number of transport blocks for eachassignment).

Maximum payload that may be accommodated by the PUCCH format configuredto be use in this subframe on a condition that no PUSCH transmissiontakes place in the subframe may be used to determine a method to applyin a particular subframe. For example, the WTRU may select the methodthat generates a number of HARQ-ACK information less than the maximum.

Maximum payload that may be accommodated by the PUSCH transmission inthis subframe may be used to determine a method to apply in a particularsubframe, such that the number of REs required to transmit HARQ-ACKinformation does not exceed a threshold.

An indication from physical layer, MAC or RRC signaling may be used todetermine a method to apply in a particular subframe. For example, afield from a PDCCH/E-PDCCH containing a downlink assignment, an uplinkgrant or containing information on a set of downlink assignments anduplink grants may be used to indicate how HARQ-ACK information may begenerated or the maximum number of HARQ-ACK bits that may be generated.

The following solutions address the issue of insufficient maximumpayload for UCI in PUCCH, including at least one of HARQ-ACK, channelstate information (CSI) and SR. In an example, an the available numberof coded bits in a PUCCH may be increased.

In some solutions, PUCCH payload may be increased by using highmodulation order symbols, for example, using modulation order higherthan that of QPSK such as 16-quadrature amplitude modulation (QAM),64-QAM, 256-QAM, and the like.

As an example, the number of coded bits carried in a single 16-QAMsymbol is 4 bits, which is twice as much compared to those of carried ina single legacy PUCCH (such as, PUCCH format 3) QPSK symbol. A legacyPUCCH format 3 payload may be encoded into 48 bits and then may bemapped into 24 QPSK symbols. As an example, if 16-QAM symbols may beused instead of QPSK, for the same number of symbols, such as, 24symbols, the PUCCH may carry 4×24=96 coded bits, which in comparison maybe twice as much of the maximum encoded bits of legacy PUCCH format 3using QPSK modulation.

The WTRU may use different modulation orders for different symbols whichmay be mapped to different PUCCH REs.

The WTRU may use different modulation orders for different symbols whichmay be mapped to different subcarriers. For example, out of 12subcarriers per PUCCH RB n subcarriers, such as, n=4, may carry QPSKmodulated symbols and (12−n) subcarrier, such as, 8, may carry 16-QAMmodulated symbols. The total number of coded bits for a PUCCH with twoPRBs (assuming all SC-FDMA symbols within the same PRB may carry thesame information) may be calculated as follows:

2×[n×2+(12−n)×4]=96−2×n   Equation (1)

All symbols mapped to the same subcarrier within the same PUCCH PRB maybe modulated using the same modulation order, for example, QPSK, 16-QAM,and the like.

A WTRU may use different encoders and/or may generate different sets ofencoded bits. Different sets of encoded bits may be mapped to differentsets of PUCCH symbols where each set of PUCCH symbols may be modulatedusing a different modulation technique, for example, QPSK, 16-QAM, andthe like. As an example, two encoders may be used to encode theinformation bits to be carried in a single PUCCH PRB, which may bereferred to as the “Encoder A” and “Encoder B”. Each encoder may have adifferent set of information bits as the encoder input. The output ofthe Encoder A may be modulated using a certain modulation technique, forexample, QPSK, and may be mapped to a certain number of PUCCHsubcarriers, such as, 4 subcarriers. The output of Encoder B may bemodulated using a different modulation technique, for example, 16-QAM,and may be mapped to a different set of PUCCH subcarriers, such as,12−8=4 subcarriers. The total number of coded bits for a PUCCH with twoPRBs (assuming all SC-FDMA symbols within the same PRB may carry thesame information) may be calculated as 88, per the formula describedearlier.

Each PUCCH encoder, for which the encoded bits may be mapped todifferent modulation orders/techniques, may have a different protectionlevel and/or robustness against channel/decoding impairments. Forexample, the encoded bits which may be ultimately mapped to 16-QAMsymbols, may have less robustness against the channel/decodingimpairments compared to the encoded bits mapped to QPSK symbols.

The WTRU may have two or more different sets of information bits withthe possibility for two or more different performance requirements. Thetwo or more different sets of information bits may be encoded using twoor more encoders and/or the encoded bits may be modulated by two or moremodulation techniques, for example, QPSK, 16-QAM, and the like. The twoor more sets of modulated symbols may be mapped to two or more sets ofsubcarriers and/or REs.

As an example, the WTRU may use HARQ ACK/NACK bundling to bundle theHARQ ACK/NACK bits of some of the component carriers and/or the WTRU maynot bundle the HARQ ACK/NACK of some other component carriers. Since anerror in the reception of the bundled HARQ ACK/NACK bit may impact theoperation of more component carriers compared to that of the error in anon-bundled HARQ ACK/NACK bit, the WTRU may assign the bundled HARQACK/NACK bits to the encoder which may be ultimately mapped to the QPSKsymbols, whereas the WTRU may assign the non-bundled HARQ ACK/NACK bitsto the encoder which may be ultimately mapped to the 16-QAM symbols.Consequently, the bundled HARQ ACK/NACK bits may have a higherprotection against channel/decoding impairments compared to non-bundledHARQ ACK/NACK bits.

The WTRU may determine a modulation scheme based on a number of codedbits that needs to be transmitted in a subframe. For example, assumingthat the same spreading scheme and number of RBs as PUCCH format 3 wouldbe used (i.e. 2 symbols per sub-carrier and 1 RB), the WTRU may transmitusing QPSK if the required number of coded bits is 48 bits, and using16-QAM if the required number of coded bits is 92 bits.

In some solutions, PUCCH payload may be increased by allocating morethan 1 resource block to a single PUCCH resource. Such solutions may bereferred to as “extended PUCCH” when described herein.

FIG. 2 is a diagram of an example of possible RE mapping for extendedPUCCH design utilizing two contiguous RBs. As shown in mapping 200, thetime and frequency dimensions are represented by the horizontal andvertical axes, respectively. In an example in mapping 200, RB#1 210 andRB#2 220 are contiguous and transmitted in the same timeslot. Thisdesign may have the benefit of preserving single-carrier property of theuplink transmission. The number of REs available to carry uplink controlinformation may essentially be doubled compared to a legacy transmissionformat utilizing a single RB.

In some solutions where PUCCH utilizes 2 RBs, the demodulation DM-RSs230 may be transmitted in the same time symbols as in a legacytransmission format, such as PUCCH format 3. Information 240 andinformation 250 may also be transmitted. This is also illustrated inFIG. 2 .

Different solutions may be envisioned for determining the sequence ofthe DM-RS, as described herein.

In a first solution, the DM-RS sequence for an extended PUCCH may begenerated from base sequences r _(u,v)(n) of length 24 that are used inlegacy systems for the DM-RS sequence of a PUSCH allocation of 2 RBs.Such base sequences may be different from the base sequences of length12 used for PUCCH. The sequence itself may be defined as a cyclic shiftof the base sequence

r _(u,v) ^((α))(n)=e ^(jαn) r _(u,v)(n)   Equation (2)

The benefits of this solution may be that the DM-RS sequence has lowpeak-to-average power ratio and it allows multiplexing of other extendedPUCCH resources using the same pair of RBs by use of different cyclicshifts of the same base sequence.

In a second solution, the DM-RS sequence for an extended PUCCH may begenerated from two concatenated base sequences of length 12. In otherwords, the DM-RS sequence used for the extended PUCCH, r_(u,v)^((α)ext)(n) may be expressed as:

r _(u1,u2,v) ^((α)ext)(n)=e ^(jαn) r _(u1,v)(n) for 0≤n<12 and  Equation (3)

r _(u1,u2,v) ^((α)ext)(n)=Ke ^(jαn) r _(u2,v)(n) for 12≤n<24,   Equation(4)

where K may be a constant of unity amplitude, possibly dependent on thegroup-sequence numbers u1 and u2, configured such that thepeak-to-average ratio of the DM-RS sequence is kept to a low value. Thegroup-sequence numbers u1 and u2 may be set to the same value u. In thiscase, the extended DM-RS sequence in this solution may be equivalent totwo concatenated DM-RS sequences of length 12 generated from the samebase sequence with different cyclic shifts and and a phase offset forthe second sequence, K=e^(jβ), for example:

r _(u,v) ^((α) ¹ ^(,α) ² ^()ext)(n)=e ^(jα) ¹ ^(n) r _(u,v)(n) for0≤n<12   Equation (5)

and

r _(u,v) ^((α) ¹ ^(,α) ² ^()ext)(n)=e ^(jα) ² ^(n+jβ) r _(u,v)(n) for12≤n<24   Equation (6)

An example benefit of this solution may be that it allows multiplexingof an extended PUCCH resource with PUCCH format 3 resources on the sameRBs, as long as the cyclic shift of the PUCCH format 3 on the first RB(or second RB) is different than (or respectively, and provided thatorthogonality is also ensured for the resources carrying information.Multiplexing with other extended PUCCH resources on the same pair of RBsmay also be possible with appropriate selection of cyclic shifts. Theset of possible combinations of cyclic shifts and and phase offset maybe restricted such that desirable properties of the DM-RS sequence aremaintained (for example, low peak-to-average power ratio). For example,utilizing a phase offset of pi/4 may result in a lower peak-to-averagepower ratio than using no phase offset.

In all the above solutions, the cyclic shifts used for DM-RS as well asthe value of the phase offset may be a function of the time symbol inwhich DM-RS is transmitted.

Processing for the information carried by the extended PUCCH may besimilar to processing used for PUCCH format 3 after modulation. Eachmodulated symbol may be spread over one sub-carrier and one time slot,resulting in a total of 48 modulated symbols or 96 coded bits if QPSK isused. This approach may have the benefit of enabling multiplexing of theextended PUCCH with PUCCH format 3 on a same RB, provided thatorthogonality of DM-RS is also achieved.

The WTRU may determine a number of RBs based on a number of coded bitsthat needs to be transmitted in a subframe. For example, assuming thatthe same spreading and modulation schemes as PUCCH format 3 would beused (i.e. 2 symbols per sub-carrier and QPSK), the WTRU may transmitover 2 RBs if the required number of coded bits is 96 bits, and over 3RBs if the required number of coded bits is 144 bits. When the number ofRB's used for PUCCH is more than 1, the WTRU may apply transformprecoding using one of the following solutions.

In a solution, the WTRU may apply discrete Fourier transform (DFT) overthe set of all transmitted sub-carriers. In case the WTRU does nottransmit over one of the RBs defined for the PUCCH transmission(according for instance to one of the solutions described in subsequentparagraphs) the DFT may not be applied to the correspondingsub-carriers. This solution may ensure that the output signal maintainsas much as possible the desirable properties of SC-FDMA (e.g., low cubicmetric).

In another solution, the WTRU may apply DFT separately over each RB.This solution may reduce receiver complexity in case there isuncertainty about whether the WTRU transmits or not on each RB.

In some solutions, PUCCH payload may be increased by spatialmultiplexing. Such solutions may be referred to as “Rank-n PUCCH”herein, where n is the number of layers. With such solutions, for thesame number of REs available for the transmission of information, thenumber of modulation symbols (and coded bits) may be increased by afactor n. The WTRU may transmit distinct DM-RS sequences for eachantenna port corresponding to a layer.

In some solutions, each DM-RS sequence transmitted for each antenna portmay be generated from a same base sequence of length 12 r _(u,v)(n). TheDM-RS sequences

r _(u,v) ^((α))(n)=e ^(jαn) r _(u,v)(n)   Equation (7)

used in a time symbol may use a different cyclic shift for each antennaport p. This approach may have the benefit that multiplexing with legacyPUCCH format 3 transmissions in the same resource block may beachievable.

When spatial multiplexing is used, the channel quality as seen by theeNode-B receiver, may be different between the two antenna ports. Insome solutions, the WTRU may therefore utilize different coding rates,coding schemes and/or modulation schemes between the two transmissionlayers to ensure that the error performance target of the at least onetype of uplink control information is met for a transmission power aslow as possible. For example, in the case of a Rank-2 PUCCH (n=2) atleast one of the following solutions may be applied: processing kinformation bits of a given type, wherein k1 information bits areencoded, modulated and mapped on a first antenna port and k2 informationbits are encoded, modulated and mapped on a second antenna port;encoding, modulating and mapping information bits of a first type on afirst antenna port and of a second type of a second antenna port;determining a modulation order (for example, QPSK or 16-QAM) for use oneach antenna port; determining a number of coded bits available on eachantenna port; and determining coding scheme (for example, block code,convolutional code, turbo) for use on each antenna port.

For example, a WTRU may have to transmit k=30 bits of a giveninformation type (such as HARQ-ACK) on a Rank-2 PUCCH. The WTRU maydetermine that k1=20 bits and k2=10 bits are encoded, modulated andmapped on the first and second antenna port respectively. The WTRU mayalso determine that QPSK is used on each antenna port, such that 48coded bits are determined to be available for each antenna port. TheWTRU may then encode 20 information bits using a coding rate of 20/48 tobe mapped on the first antenna port and 10 information bits using acoding rate of 10/48 to be mapped on the second antenna port.

The WTRU may determine at least one of the above parameters using atleast one of the following solutions. The WTRU may use an indicationreceived from higher layer signaling. The WTRU may use an indicationreceived from at least one field of DCI received on PDCCH or E-PDCCH.For example, the DCI may be a DCI containing one of the downlinkassignments indicating a transport block for which HARQ-ACK is to betransmitted in the PUCCH transmission. The indication may include one ormore of the following: an indication of a number or ratio of informationbits to be encoded and mapped on each layer, (for example, a 2-bit fieldmay indicate that the ratio is either one third, one half, two thirds orthree fourth on the first antenna port and the remaining on the secondantenna port (where the number of bits may be rounded up or down)); theA/N resource indicator (ARI) field, overloaded to include the above (theARI field may be equivalent to, or may reuse the same resources as, atransmitter power control (TPC) field received in downlink controlinformation for an SCell); an indication of whether QPSK or 16-QAM maybe used for each antenna port; and an indication of the channel qualityimbalance between the two antenna ports, expressed, for example, interms of signal-to-interference ratio (SINR) ratio or difference in dB,or in terms of required difference between transmitted energy perinformation bit on each antenna port. The WTRU may use at least oneresource index associated with the N-rank PUCCH, which may be indicatedusing an ARI field in combination with higher layer signaling. Thenumber of information bits and modulation to for each antenna port maybe configured as part of a resource configured by higher layers.

In examples, pre-coding may be used. In some examples, a WTRU equippedwith more than one antenna port for the uplink may employ precodingsimilar to precoding applied to PUSCH. This may allow spatialmultiplexing of PUCCH transmissions of multiple WTRU's on the samefrequency and time resource. The pre-coding matrix applicable to thePUCCH transmission may be provided with downlink control signaling, suchas in at least one PDCCH/E-PDCCH containing PDSCH assignments for whichfeedback is being provided in the subframe.

In some examples, DFT-S-OFDM with a smaller spreading factor may beused. In some solutions, PUCCH payload may be increased by spreading amodulation symbol over a smaller number of resource elements in aDFT-S-OFDM structure. For example, 48 modulation symbols spread over 3time symbols may be mapped on the PUCCH and where the number of timesymbols used for DM-RS is reduced to 2.

In some solutions, the time symbols used for DM-RS may be maintained inthe same time symbols as in legacy PUCCH format 3 to maintain thepossibility of multiplexing with legacy PUCCH transmissions of thisformat in the same RB. In such a framework several possibilities may beenvisioned for the spreading of modulation symbols to time symbols overa subcarrier, such as but not limited to: 10 modulation symbols, each ona single time symbol (for example, no spreading); 5 modulation symbols,each spread over 2 time symbols; 4 modulation symbols, of which 2 may bespread over 3 time symbols and 2 over 2 time symbols; and 3 modulationsymbols, of which 2 may be spread over 3 time symbols and 1 over 4 timesymbols.

In case of a shortened PUCCH transmission, where the last time symbol isnot available, the number of time symbols onto which a modulation symbolis spread may be reduced by 1 for one of the modulation symbols. Theimpacted modulation symbol is preferably one that is spread over alarger number of time symbols in a non-shortened PUCCH transmission.

The exact mapping of modulation symbols to time symbols within asub-carrier (and therefore the spreading factor) may be parameterized tosupport a maximum payload value for PUCCH depending on this parametervalue. The parameter may be derived from a PUCCH resource index orconfigured along with a PUCCH resource index.

Where separate coding is applied to a different subset of UCI bits,modulation symbols spread over a larger number of time symbols withinthe PUCCH (for example, the 2 modulation symbols per subcarrier whichare spread over 3 time symbols instead of 2) may be used to carry codedbits for the UCI requiring higher robustness.

The WTRU may determine a spreading scheme based on a number of codedbits that needs to be transmitted in a subframe. For example, the WTRUmay spread 5 modulation symbols per sub-carrier if the required numberof coded bits is 120 bits, and 3 modulation symbols per sub-carrier ifthe required number of coded bits is 72 bits.

In an example, selection of codebook, resource and transmission formatand parameters may be used. The WTRU may determine a PUCCH transmissionformat and possibly associated parameters for use in a particularsubframe. A PUCCH transmission format may be characterized by a totalnumber of coded bits and how the set of coded bits (or each subset ofcoded bits, if applicable) may be modulated, spread and mapped tophysical resources (possibly including spatial multiplexing).

The PUCCH transmission format may include at least one of: a legacyPUCCH format such as 1, 1a, 1b, 2, 3, and the like; and a new PUCCHformat supporting higher payload, such as a format based on one or acombination of techniques described in the above (higher ordermodulation, larger BW, spatial multiplexing or reduced spreading).

The selection of a format and associated parameters may be based on atleast one of the following. The selection may be based on the number ofinformation bits for different types of UCI to be transmitted on PUCCH(including multiple types of HARQ-ACK, CSI, SR). For example, theselection may be based on the presence or not of different types of UCIto be transmitted on PUCCH. Also, the selection may be based on anindication received from physical layer or higher layer signaling, suchas a PDCCH/E-PDCCH containing a DL assignment or information about DLassignments. For example, the indication may contain a parameterindicating a number of modulation symbols to be mapped per subcarrier(or a spreading factor or set of spreading factors), a parameterindicating a modulation type (such as QPSK or 16QAM), and/or a parameterindicating a number of layers for the PUCCH transmission (rank).Further, the selection may be based on the method used for generatingHARQ-ACK information bits to be transmitted in the PUCCH. In addition,the selection may be based on an indication received from physical layeror higher layer signaling of at least one codebook property, asdescribed herein. The selection may also be based on a subset offeedback groups transmitted in a subframe, as described herein. Further,the selection may be based on dynamic scheduling of uplink resources forUCI feedback such as described herein, including methods related to UCIscheduling information as described herein, for example, using DCI(UCI)similar to that described herein.

In some solutions, the WTRU may determine all properties of atransmission format (including at least one of modulation, number ofRBs, spreading, spatial multiplexing) based on a required number ofcoded bits and a mapping based on a pre-determined set of number ofcoded bits, number of information bits and/or subsets of feedbackgroups. For example, the WTRU may determine the transmission formatbased on a table similar to Table 1.

TABLE 1 Number of modulated Number of symbols spread by coded bitsNumber of RBs sub-carrier Modulation scheme  48 1 2 QPSK  72 1 3 QPSK 96 2 2 QPSK 144 2 3 QPSK 192 2 2 16-QAM 288 2 3 16-QAM

In this example, the WTRU may determine a number of coded bits based forinstance on a total number of information bits and a maximum codingrate, as described in subsequent paragraphs. For example, if the WTRUdetermines that the required number of coded bits is 144, the WTRU mayemploy QPSK modulation on the coded bits, spread the modulated symbolssuch that 3 symbols are spread over each sub-carrier, and map theresulting signal over 2 RBs.

In some solutions, the WTRU may select some properties of thetransmission format based on a dynamic indication, such as receiving anARI or another field from PDCCH/E-PDCCH. For example, a resourceindicated by a received ARI may have 1 RB. If the required number ofcoded bits is 96 bits, the WTRU may determine that the spreading shouldbe such that 4 modulation symbols are spread per sub-carrier, allowingfor 96 coded bits in the RB. In case the resource indicated by thereceived ARI would have 2 RBs, the WTRU may determine that the spreadingshould be such that 2 modulation symbols are spread per sub-carrier,allowing for 96 coded bits in 2 RBs. Further examples of such dynamicaspects are described herein.

In an example, a dynamic determination of codebook properties may beused. In some solutions, the WTRU may determine at least one property ofthe set of information bits for HARQ feedback and possibly other UCI(e.g., the codebook) based on semi-static and/or dynamic aspects. Thesolutions may allow minimization of the amount of resources used for thetransmission of such information. Further examples of such dynamicaspects are described herein.

By extension, the solutions described below may also be used todetermine a PUCCH format, a PUCCH resource or a power control methodthat may be associated with a codebook property (such as the codebooksize). For example, the WTRU may determine that a first PUCCH format(and/or power control method) is used if the codebook size is smallerthan a first value and that a second PUCCH format is used if thecodebook size is larger than or equal to a first value but smaller thana second value, and so on.

At least one of the following codebook properties may be determined. Thenumber of information bits of the codebook may be determined. The orderof the information bits of the codebook, for example in terms of whichtransport block(s) of which cell(s) or cell group(s) are mapped to agiven position of the codebook, may be determined. The interpretation ofeach information bit (or set thereof) may be determined, such as whetherthe bit(s) represents: the ACK or NACK outcome of the decoding of atransport block received on a specific cell, cell group, and/orsubframe; and/or an indication of cell(s) or cell group(s) orsubframe(s) over which bundling is applied or not. A source codingscheme that may be applied (e.g., Huffmann encoding) may be determined.A channel coding scheme applied to the codebook (e.g., Reed-Muller,turbo or convolutional) may be determined.

FIG. 3 is a diagram of an example selection process for a PUCCH formatbased on the size and type of feedback. In an example shown in process300, a WTRU may receive a plurality of transport blocks over a set of aplurality of configured carriers and generate HARQ-ACK feedback 310 andCSI feedback 320 for the plurality of transport blocks. Further, thenumber of information bits needed for HARQ-ACK feedback 310, which maybe represented by n, and the number of information bits needed for CSIfeedback 320, which may be represented by m, may be combined (e.g.,concatenated) by the WTRU 330. The WTRU may generate a feedback messagethat includes the number of HARQ-ACK feedback bits to use for theHARQ-ACK feedback and the number of CSI feedback bits to use for the CSIfeedback. The WTRU may then determine the possible PUCCH format based onthe content of the feedback 340. For example, this PUCCH formatdetermination may be made based on the number of HARQ-ACK feedback bitsand the number of CSI feedback bits. The WTRU may transmit the feedbackmessage using the determined PUCCH format.

For example, if HARQ-ACK feedback is present and therefore n>0 and ifCSI feedback is present and therefore m>0, then a first PUCCH format,such as PUCCH format x, or a second PUCCH format, such as PUCCH formaty, may be selected 350. Also, if HARQ-ACK feedback is not present andtherefore n=0 and only CSI feedback is present and therefore m>0, thenPUCCH format x or a third PUCCH format, such as PUCCH format z, may beselected 360. Further, if HARQ-ACK feedback is present and therefore n>0and if CSI feedback is not present and therefore m=0, then PUCCH formatx or a fourth PUCCH format, such as PUCCH format w may be selected 370.

In the case that PUCCH format x or PUCCH format y is selected 350, theWTRU may then compare the number of information bits of the feedbackpayload to a first threshold 355, such as B₁. If the feedback payload isgreater than the first threshold and therefore n+m>B₁, then PUCCH formatx may be selected 356. Further, if the feedback payload is less than orequal to the first threshold and therefore n+m≤B₁, then PUCCH format ymay be selected 358. The WTRU may transmit the feedback message usingthe determined PUCCH format.

In the case that PUCCH format x or PUCCH format z is selected 360, theWTRU may then compare the number of information bits of the feedbackpayload to a second threshold 365, such as B₂. If the feedback payloadis greater than the second threshold and therefore m>B₂, then PUCCHformat x may be selected 366. Further, if the feedback payload is lessthan or equal to the second threshold and therefore m≤B₂, then PUCCHformat z may be selected 369. The WTRU may transmit the feedback messageusing the determined PUCCH format.

In the case that PUCCH format x or PUCCH format w is selected 370, theWTRU may then compare the number of information bits of the feedbackpayload to a third threshold 375, such as B₃. If the feedback payload isgreater than the third threshold and therefore n>B₃, then PUCCH format xmay be selected 376. Further, if the feedback payload is less than orequal to the third threshold and therefore n≤B₃, then PUCCH format w maybe selected 377. The WTRU may transmit the feedback message using thedetermined PUCCH format.

A codebook property may be dependent at least on semi-static (or static)information, such as a number of configured carriers (or cells), asubframe configuration, a grouping of cells in cell groups, a number oftransport blocks that may be received in a given cell, a transmissionmode used in a given cell, and a HARQ feedback scheme configured to beutilized in a cell or group of cells (such as whether bundling within oracross subframes or cells is applied, or whether a HARQ feedbacksolution as described earlier is applied).

The WTRU may also determine a codebook property as a function ofinformation that may change more dynamically, such as: the activationstate of a cell or a cell group; whether radio link problems or radiolink failure occurred for a cell group or was reported for a cell group;whether PDSCH is known to not have been transmitted from the network fora cell or a group of cells, or alternatively known to have beentransmitted from the network; the dynamic subframe configuration (uplink(UL) or DL) in a cell; and DL control information received in asubframe.

For example, the WTRU may determine that a codebook only includes HARQfeedback for cells or groups of cells that are in an activated state orfor which radio link failure was not reported. The WTRU may alsodetermine that a codebook only includes HARQ feedback for cells, groupsof cells or subframes from which the WTRU determines that PDSCH may havebeen transmitted. In this case the WTRU may determine the codebook sizeand the bit position(s) accordingly. For example, in case of 10configured cells and 2 transport blocks per cell, if the WTRU determinesthat PDSCH may have been transmitted from cells 2, 3 and 6 only, thefirst two bits may correspond to HARQ feedback for cell 2, the two nextbits may corresponding to HARQ feedback for cell 3, and so on for acodebook size of 6 bits.

The WTRU may make the determination that PDSCH may have been transmittedby using one of the following solutions. The WTRU may receive anindication of the cells, cell groups, transport blocks and/or subframesin which PDSCH may be transmitted from downlink control signalingincluded in PDCCH or E-PDCCH. The indication may consist of a field ofwhich each possible value indicates a subset of cells, cell groupsand/or subframes in which PDSCH may be transmitted (or may not betransmitted). The subset associated with each value may be predeterminedor configured by higher layers. The subset may also be a function of thecell or cell group in which the signaling is received, or of the cell(s)or cell group(s) indicated in the same PDCCH or E-PDCCH in which thefield is contained.

For example, if the field size is two bits, the value “00” may indicatethat PDSCH may be received only in the cell(s) or cell group(s) forwhich PDSCH is scheduled in this PDCCH or E-PDCCH; the value “11” mayindicate that PDSCH may be received in any configured cell or cellgroup; the value “01” may indicate that PDSCH may be received in a firstset of cell groups configured by higher layers, and the value “10” mayindicate that PDSCH may be received in a second set of cell groupsconfigured by higher layers.

In another example, the cell index of one (or more) serving cell wherePDSCH is transmitted may be used in combination with the indicationvalue to determine the codebook. In this example, every DCI with adownlink assignment may transmit the same indication. The indicationvalue may be mapped to different sets of cells and/or carriers and/ortransport blocks for which a WTRU may be expected to feedback A/N. Thedetermination of the appropriate set based on the indication, may be afunction of the serving cell ID of at least one cell where a PDSCH istransmitted.

Table 2 provides an example of a relationship between an indication andsets of cells for which a WTRU may report A/N, as a function of theserving cell. Basically, the WTRU may determine the appropriate set as afunction of the indication and that of the set of which at least oneserving cell where a PDSCH is transmitted.

TABLE 2 Index Value Set of Cells for Which to Report HARQ A/N Feedback000 All cells 001 Select the set that includes at least one cell(s)where PDSCH is scheduled among: {1, 2, 3, 4,5, 6, 7, 8}, {9, 10, 11, 12,13, 14, 15, 16}, {17, 18, 19, 20, 21, 22, 23, 24}, {25, 26, 27, 28, 29,30, 31, 32} 010 Select the set that includes at least one cell(s) wherePDSCH is scheduled among: {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16}, {17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,31, 32} 011 Select the set that includes at least one cell(s) wherePDSCH is scheduled among: {1, 2, 3, 4, 5, 6, 7, 8, 25, 26, 27, 28, 29,30, 31, 32}, {9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,24} 100 Select the set that includes at least one cell(s) where PDSCH isscheduled among: {1, 2, 3, 4, 5, 6, 7, 8, 17, 18, 19, 20, 21, 22, 23,24}, {9, 10, 11, 12, 13, 14, 15, 16, 25, 26, 27, 28, 29, 30, 31, 32} 101{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,21, 22, 23, 24} 110 {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,16, 25, 26, 27, 28, 29, 30, 31, 32} 111 (1, 2, 3, 4, 5, 6, 7, 8, 17, 18,19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32}

In case HARQ-ACK is to be reported for more than 1 subframe (e.g., incase of TDD), in one solution, the indication may represent the entirecodebook over all subframes and cells regardless of the subframe inwhich it is received. Alternatively, the indication may represent theportion of the codebook corresponding to the subframe in which it isreceived. Alternatively, the indication may represent the portion of thecodebook corresponding to subframe(s) up to and including the subframein which it is received. For example, the indication may represent the aset of cell(s) or cell group(s) where PDSCH may be received in anysubframe up to and including the subframe in which the indication isreceived.

The meaning of an indication (e.g., the set of transport blocks and/orcells and/or carriers and/or subframes for which a WTRU is expected tofeedback HARQ A/N) may depend on other, possibly implicit, factors. Forexample, a WTRU may receive a specific codepoint or bitmap in anindication, and the WTRU may map such indication to a different codebookdepending on at least one of the following. The WTRU may map such anindication to a different codebook depending on a timing of thetransmission of the indication. For example, the subframe number may beused in conjunction with the indication. In another example, thespecific subframe of a set of subframes for which feedback is reportedin a specific subframe (in TDD) may be used. The WTRU may also map suchan indication to a different codebook depending on another parameter ofa DCI including the indication. For example, a combination of a TPCcommand and a new indication may be used. In another example, aparameter of the search space (e.g., whether it is common search spaceor WTRU-specific search space, or the CCE of the search space) of a DCImay be used in combination with the indication value. Further, the WTRUmay also map such an indication to a different codebook depending on thePUCCH format and/or resources indicated in a downlink assignment.

In the above, the indication may be contained in a subset or alldownlink assignments. The indication may also be contained in one ormore PDCCH/E-PDCCH (or DCI(s)) dedicated to the provision of schedulinginformation for UCI as described herein.

In another example, the network may indicate which pre-configuredgroup(s) of carriers contain at least one downlink assignment. Thus, thenumber of NACK bits corresponding to non-scheduled carriers (the “known”NACKS) may be reduced when there is no downlink assignment scheduled incertain groups of carriers. The size of the codebook can therefore bedramatically reduced, although it may still contain a (smaller) numberof NACKS from non-scheduled carriers. The reduction of the size of thecodebook improves not only performance from a power perspective but alsoPUCCH resource usage.

Another example is illustrated in Table 3 for a WTRU configured with 32carriers. In this example, one of the codepoints of the indicator (00)may indicate “all carriers” to allow the WTRU be scheduled on allcarriers. Another codepoint (01) may indicate 4 disjoint groups of 8carriers. The specific group to select may be determined based on whichcarriers the assignments are received for. The two other codepoints (10)and (11) may indicate different groups of 16 carriers, or possiblygroups where the order of carriers is modified as in Option 1. The exactmapping may be configured by higher layers to maximize schedulingflexibility and performance. Additional flexibility may also be obtainedusing a field with more than 2 bits. One possibility to minimizeadditional overhead may be to use a single field for ARI and CodebookIndicator.

TABLE 3 Codebook Indicator Value Set of Carriers for Which to ReportHARQ A/N Feedback 00 All carriers 01 {1, 2, 3, 4, 5, 6, 7, 8} or {9, 10,11, 12, 13, 14, 15, 16} or (17, 18, 19, 20, 21, 22, 23, 24} or {25, 26,27, 28, 29, 30, 31, 32} 10 {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16} or (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,31, 32} 11 {1, 2, 3, 4, 5, 6, 7, 8, 25, 26, 27, 28, 29, 30, 31, 32} or{9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24}

In an example, not all carriers of an indicated group may need to bescheduled. The WTRU may indicate “NACK” when no DL assignment isdetected for a carrier included in the indicated group.

FIG. 4 is a diagram of an example of a HARQ A/N codebook determination.In an example shown in diagram 400, the WTRU may receive downlinkassignments for a sub-set of carriers within a set of carriers 410. Forexample, the WTRU may receive downlink assignments for the sub-set ofcarriers 9, 10, 13, 14, 15 and 16 with codebook indicator “01” in everyDL assignment. The WTRU may miss DL assignment for carrier 12. The WTRUmay not receive an assignment for carrier 11, which may have noassignment. The WTRU may use the codebook carrying HARQ A/N for carriers420, such as carriers {9, 10, 11, 12, 13, 14, 15, 16}, and include NACKfor carriers 11 and 12.

An indication may include at least one downlink assignment index (DAI)received as part of downlink control information associated with eachPDSCH transmission. In this case, the WTRU may order the received PDSCHfor each cell and subframe according to a pre-determined rule (forexample, by cell index first and subframe second, or vice-versa). TheWTRU may include HARQ A/N bits in the codebook for each received PDSCH(unless it was determined that HARQ A/N should not be included based onpreviously described solutions), and include HARQ A/N bits (with value“NACK”) for each PDSCH determined to be missing based on the differencebetween consecutive DAI values in the sequence. For example, the numberof missing PDSCH may be determined to be (N−1) mod M where N is thedifference between consecutive DAI values in the sequence and M is thenumber of possible DAI values.

An indication may include a field received as part of downlink controlinformation associated with at least one PDSCH transmission. The fieldmay indicate the final downlink assignment of a group of downlinkassignments, possibly assigned in or for a specific subframe. One valueof the field (for example, ‘0’) may indicate that the assignment is notthe final assignment, and another value of the field (for example, ‘1’)may indicate that the assignment is the final assignment of the groupand/or subframe and/or component carrier. This may enable the WTRU toknow when to stop blind detection in a subframe and also to know if ithas detected the final assignment.

In some solutions, the indication associated with the final (or last)assignment may be derived from the value of a field that may also beused to indicate other types of information. For example, the indicationmay be derived from at least one value of the ARI and/or of the TPCcommand for the PUCCH received in one or more PDCCH/E-PDCCH(s), or fromat least one value of a PUCCH format indicator, according to at leastone of the following.

The WTRU may identify an assignment as the final assignment if the valueof the ARI for this assignment is different from at least one otherassignment of a set. The set may consist of all assignments of asubframe or all assignments. In this case, the value of the ARI (or ofthe TPC command for the PUCCH) for this assignment may not be directlyused to indicate an index to a PUCCH resource. The determination of anassignment as the final assignment may be subject to at least one of thefollowing additional conditions.

In an example, the number of other assignments, possibly only in thesame subframe, may be at least one. In another example, the at least oneother assignment may be assignments that are preceding the finalassignment according to a pre-defined sequence (e.g., carrier first,subframe second). In a further example, the at least one otherassignment may include at least one assignment that does not correspondto the primary cell. In still another example, the value of the ARI forthe final assignment may be a fixed or configured value. In yet anotherexample, the value of the ARI for the final assignment may be related tothe value of the ARI in other assignments. For example, the value of theARI of the final assignment may indicate a PUCCH resource with a numberof RB's smaller than or equal to the PUCCH resource indicated by thevalue of the ARI in other assignments. Further, the value of the ARI ofthe final assignment may be the sum of the ARI decoded in otherassignments, plus a fixed or configured value (or XOR'ed with a fixed orconfigured value). For instance, the value of the ARI of the finalassignment may be one (1) plus the value of the ARI in other assignments(modulo the number of possible ARI values).

In case the WTRU does not detect the final assignment based on one ofthe above solutions, the WTRU may consider that the codebook isundetermined and apply actions according to solutions described in otherparagraphs. Alternatively, the WTRU may append at least one NACK (or“0”) to the codebook such that the total size of the codebookcorresponds to a valid size among a set of pre-defined or configuredvalid sizes.

An indication may consist of a field received as part of downlinkcontrol information associated with each PDSCH transmission. The fieldmay indicate to the WTRU the remaining number of assignments to beexpected after the detection of a current assignment, within a group ofdownlink assignments (possibly for a subframe and/or a componentcarrier). The WTRU may better determine missing PDSCH and may also aNACK value for any missing PDSCH in the appropriate location of afeedback report. In another solution, the field may indicate the totalnumber of downlink assignments in a group of downlink assignments and/ora subframe and/or a component carrier. The WTRU may determine the totalnumber of missing PDSCH and may indicate this to the serving cell in afeedback report.

An indication may consist of a field received as part of downlinkcontrol information associated with each PDSCH transmission, for examplea DAI. The DAI may serve as an ascending counter ordered along aparameter of the serving cells (e.g., the DAI may serve as a cumulativecounter of total assignments up to a current assignment, counted in thedirection of increasing serving cell index). For example, assuming a2-bit DAI, and with serving cells ordered in increasing serving cellindex, a first assignment on a first serving cell (e.g., a serving cellwith lowest serving cell index) may have DAI=00, a second assignment ona second serving cell (e.g., a serving cell with second lowest servingcell index) may have DAI=01, and so on.

In another solution, the DAI may serve as a descending counter orderedalong a parameter of the serving cells (e.g., the DAI may serve as acounter of the remaining assignments in the direction of increasingserving cell index). For example, assuming a 2-bit countdown DAI, andwith serving cells ordered in increasing serving cell index, a lastassignment (e.g., an assignment on a serving cell with highest servingcell index) may have countdown DAI=00, a second to last assignment(e.g., an assignment on a serving cell with highest serving cell indexremaining) may have countdown DAI=01, and so on.

The counters may increment by unit values or may not have unit countingsteps. For example, the decreasing counter of remaining assignments mayrepeat a DAI value for some consecutive assignments. For example thedecreasing counter of remaining assignments may repeat the same valuefor P consecutive assignments. In an example, if we assume 10 servingcells with assignments, and P=3, the countdown DAI may be assigned asfollows (in order of increasing serving cell index): 11 10 10 10 01 0101 00 00 00. In such a solution, a WTRU may expect the final P=3assignments to have a countdown DAI of 00. In such a solution, a WTRUmay be able to resolve whether it has successfully received a lastdownlink assignment. However, if one of the assignments with a countdownDAI is missing, a WTRU may have to report NACK for all P=3 consecutiveassignments sharing the same countdown DAI given that it may not knowwhich of the P=3 consecutive assignments is missing.

A hybrid solution may be possible, where both an increasing cumulativecounter of assignments, and a decreasing counter of remainingassignments are used. For example a unit step increasing counter may beused (e.g., a cumulative counter of assignments where the DAI isincreased by one for every assignment) and a repeating counter ofremaining assignments may be used (with P repetitions). For example,assuming 2-bit cumulative and countdown DAIs, ten assignments may havethe following total DAI values (where the first two bits represent thecumulative DAI using unit step increments and the last two bitsrepresent the countdown DAI using P=3): 0011 0110 1010 1110 0001 01011001 1100 0000 0100. In this case, from the cumulative counter the WTRUmay determine what, if any, assignment is missing, except for any2^(N+i) consecutive missing assignments (where N is the size in bits ofthe cumulative DAI and i is an integer greater than or equal to 0)and/or any last missing assignment. Also, from the repeating anddecreasing counter of remaining assignments, the WTRU may determine ifup to P*2^(M) consecutive assignments are missing (where M is the sizein bits of the countdown DAI), as well as if the last downlinkassignment is missing. Combining the two DAIs, the WTRU may resolve anyconsecutive assignments except for those that are greater than thelowest common multiples of P*2^(M) and 2^(N). The values of M and N neednot be equal. For example, a situation where the cumulative counter usesN=2 bits, and the decreasing counter of remaining assignments uses M=1bit and a repetition of P=3, may lead to a WTRU being able to resolvewhether a last assignment is missing, and any other missing assignmentsexcept for 12 or more consecutive assignments.

The field may also indicate other information relevant to HARQ feedbackfor each value, such as an indication of the format and/or resourceindex of the PUCCH to transmit on (“ACK/NACK resource indicator”). Forexample, if the field size is three bits, the value “010” may indicatethat PDSCH may be received in a first set of cell groups configured byhigher layers and that transmission of HARQ feedback takes place over acertain PUCCH format and a first value of the resource index configuredby higher layers; the value “011” may indicate that PDSCH may bereceived in first set of cell groups configured by higher layers andthat transmission of HARQ feedback takes place over a second value ofthe resource index configured by higher layers, and so on.Alternatively, information about PUCCH resource index or indices to usemay be provided in a separate field or in a separate PDCCH or E-PDCCH.

The same value of the indication may be received from more than onePDCCH or E-PDCCH (i.e., in any cell from which the WTRU receives a PDSCHassignment), to ensure robustness against missed detections. Theindication may also be contained in a PDCCH or E-PDCCH of a specific DCIformat in a specific cell or search space independently of other PDCCHor E-PDCCH containing PDSCH assignments for this WTRU. For example, theindication may be contained in a PDCCH received in a common searchspace. The indication may be valid for a duration of one subframe ormore than one subframe (such as one frame).

In an example, a generalized indicator may be used. An indication mayconsist of a field which may be interpreted either as a downlinkassignment index (DAI) or as a codebook indicator or codebook sizeindicator depending on its specific value, or depending on the value ofan associated flag or field. For example, the indication may consist ofa field of N bits, where the interpretation of N−1 bits depends on thevalue of a specific bit. Table 4 provides an example.

In a further example, the codebook size values may be pre-defined orconfigured by higher layers.

TABLE 4 Value Interpretation 000 DAI with value 00 001 DAI with value 01010 DAI with value 10 011 DAI with value 11 100 Codebook size #1 101Codebook size #2 110 Codebook size #3 111 Codebook size #4

In another example, the codebook determination may use DAI and sizeindicators. In some examples, the WTRU may determine a codebook based onzero or more DAI(s), and zero or more codebook indicator(s) or codebooksize indicator(s) received from downlink assignment(s). In suchsolutions, the WTRU may determine a codebook (or portion thereof) basedon the received DAI(s) and verify that this codebook (or portionthereof) is consistent with any applicable received codebook indicator.In case the WTRU determines that the DAI-codebook is consistent with thereceived codebook indicator, the WTRU may transmit HARQ-ACK according tothe DAI-codebook. Otherwise, the WTRU may transmit other informationand/or perform other actions as will be described herein.

A received codebook indicator may be applicable to the entire HARQ-ACKcodebook or to a subset of the HARQ-ACK codebook. In the latter case,the subset may correspond to the downlink assignment(s) received in thesame subframe as the one where the codebook indicator is received.Alternatively, the subset may correspond to the downlink assignments(s)received in the subframe(s) preceding and including the subframe wherethe codebook indicator is received. Similarly, a DAI-codebook may beapplicable over the entire HARQ-ACK codebook or to a subset.

A codebook indicator may indicate a range of possible codebook sizes, aset of possible codebook sizes or a specific size. For example, aspecific codepoint of the indicator may correspond to a range of sizesbetween 21 bits and 50 bits. In this case, the WTRU may determine thatthe DAI-codebook is consistent with an applicable received codebookindicator if its size is within the indicated range, or if it is equalto the indicated size. A codebook indicator may correspond to a PUCCHformat indicator, where the indication of a PUCCH format implicitlyindicates a range of possible sizes for the codebook. For example, anindication of PUCCH format 3 may implicitly indicate that the codebooksize is below or equal to 21 bits.

In some examples, the WTRU may implicitly derive a range or set ofcodebook sizes from other properties or fields of downlink controlsignaling instead of an explicit codebook indicator. For example, theWTRU may derive a range of possible codebook sizes from an indication ofthe number of RBs allocated to PUCCH, or from a resource indication (forexample, an ARI) for a PUCCH, possibly in combination with a PUCCHformat indicator. The set of possible codebook sizes for a certainnumber of RB's of a PUCCH or for a certain value of ARI may bepre-defined or configured by higher layers. For example, the set ofpossible codebook sizes may be configured as {16, 32, 48, 64, 80, 96,112, 128} for ARI=2 and as {24, 40, 56, 72, 88, 104, 120} for ARI=3.

A specific downlink assignment may contain a codebook indicator, a DAIor both a codebook indicator and a DAI. When a downlink assignment doesnot indicate a DAI (for instance, when a generalized indicator has avalue not corresponding to a DAI), the expected DAI value in the nextreceived downlink assignment may be incremented as if a DAI wasreceived.

When the WTRU determines that the DAI-codebook is not consistent withthe codebook indicator for at least one portion of the codebook, theWTRU may adjust the size of the codebook for the at least one portion toa value corresponding with the codebook indicator, if such indicatorindicates a specific size. The WTRU may indicate NACK for all bits ofthe at least one portion. In case the WTRU determines that theDAI-codebook is not consistent with the codebook indicator for at leastone portion of the codebook but cannot determine the correct size of thecodebook (e.g., if the indicator only indicates a range of sizes), theWTRU may consider that the codebook is undetermined and may performactions described herein.

In the above, an indication may consist of the value of a field includedin the payload of the DCI, or of the value of a field used to mask asubset or all bits of the CRC.

In some examples, the codebook may be indicated by the network to theWTRU in a dynamic manner. For example, a codebook indicator may beincluded in at least one of all the downlink assignments whosetransmissions map to a single HARQ A/N feedback resource. The meaning ofthe codepoints in the codebook indicator may be configured by thenetwork, possibly semi-statically. For example, an RRC command may beused to indicate to the WTRU the possible codebooks for each codepoint(where the WTRU may select the appropriate codebook based on theindicator and at least one serving cell). In order to improve thegranularity of the codebook, and thus possibly augment the gains ofusing a dynamic codebook, the number of indicator bits may be increased.For example, 4 indicator bits may be used, and each one of the 16possible codepoints may map to a plurality of codebooks depending on theserving cell of at least one assignment. Such configuration may requirelarge RRC payload and may not be tenable.

The meaning of a codebook indicator for a codebook may be determined bya combination of the configuration of a subset of codepoints and of atleast one serving cell. For example, a WTRU may be configured, possiblyby the RRC with a number of sets of carriers (e.g., 4 sets of up to 8carriers each, or 8 sets of up to 4 carriers each, or 16 sets of up to 2carriers each, or 32 sets of 1 carrier each). The sets may bepre-determined, or may be explicitly configured by the network. Or thesets may be determined at the WTRU by a network-transmitted indicator oftotal number of sets, and the WTRU splitting up the configured carriersin a pre-determined or pre-configured manner (e.g., the WTRU may orderthe carriers by an index such as cell index and then may evenly splitthe carriers into the configured number of sets). The WTRU may also beconfigured (possibly semi-statically) with a table mapping the first x(e.g., x=2) bits of the indicator to sets of carriers. The otherremaining y bits of the indicator (e.g., y=2) may be determined as afunction of the table used for the first x bits, and possibly as afunction of at least one serving cell.

As an example, the network may indicate to the WTRU that it is to use 4sets of carriers. Each set of carriers may include up to 8 carriers(e.g., set A={1,2,3,4,5,6,7,8}, set B={9,10,11,12,13,14,15,16}, setC={17,18,19,20,21,22,23,24} and set D={25,26,2,28,29,30,31,32}). TheWTRU may also be configured (possibly semi-statically) with a tablemapping the first 2 bits of the indicator to different sets, forexample, as shown in Table 5.

TABLE 5 Index Value First 2 bits) Set of Cells for Which to Report HARQA/N Feedback 00 Select the set that includes at least one cell wherePDSCH is scheduled among: A or B or C or D 01 Select the set thatincludes at least one cell where PDSCH is scheduled among: AB or CD 10Select the set that includes at least one cell where PDSCH is scheduledamong: AC or BD 11 Select the set that includes at least one cell wherePDSCH is scheduled among: AD or BC

The meaning of the last two bits of the indicator may be determined byusing the empty set for at least one codepoint (e.g., ‘00’) and then forall other codepoints using the complement of the sets determined fromthe at least one serving cell (where the complement of A is denoted byAc and is given by BCD in this example). Table 6 shows an example of themeaning of the last 2 bits of the codebook indicator.

TABLE 6 Index Value (Last 2 bits) Set of Cells for Which to Report HARQA/N Feedback 00 Empty set 01 Complement of set obtained by codepoint‘01’ in first two bits of index 10 Complement of set obtained bycodepoint ‘10’ in first two bits of index 11 Complement of set obtainedby codepoint ‘11’ in first two bits of index

For example, a WTRU configured with Table 5 for the first two bits ofthe indicator and receiving an assignment from a cell in set A mayinterpret the first two bits of the indicator from Table 7 and may theninterpret the last two bits of the indicator from Table 8. The over-allcodebook may be determined from the union of sets obtained from thefirst two and last two bits of the codebook indicator. In this example,if the WTRU decodes an assignment from a cell in set A and is also giventhe codebook indicator codepoint 0110, then from the fact that it has atleast one cell in set A, the meaning of the first two bits (01) may meanset AB and the meaning of the last two bits (10) may mean set BD.Therefore in this case, the codebook may include the union of the twosets and thus all cells in sets A, B and D.

In another example, the WTRU may decode an assignment in a cell in set Awith codebook indicator (0000), then from Table 7 and Table 8, it may bedetermined that the codebook is the union of set A and the empty set,and therefore includes all cells in set A.

TABLE 7 Index Value Set of Cells for Which to Report HARQ AIN (First 2bits) Feedback 00 A 01 AB 10 AC 11 AD

TABLE 8 Index Value Set of Cells for Which to Report HARQ AIN (Last 2bits) Feedback 00 Empty set 01 (AB)c = CD 10 (AC)c = BD 11 (AD)c = BC

In another example, the sets for every codepoint in Table 5 may bedetermined by a WTRU as a function of the total number of sets and of apre-configured or pre-determined formula. For example, codepoint ‘00’may be any single set, whereas codepoint ‘01’ may be pairs of two sets(e.g., elect the set that includes at least one cell transmitting theindex from: AB or CD or EF or GH or . . . ), codepoint ‘10’ may begroups of three sets (e.g., select the set that includes at least onecell transmitting the index from: ABC or DEF or GHI or . . . ),codepoint ‘1’ may be groups of four sets (e.g., select the set thatincludes at least one cell transmitting the index from: ABCD or EFGH or. . . ).

In a further example, the WTRU may make a determination of order of theinformation bits in the codebook. The WTRU may make a selection of acodebook permutation to optimize decoding performance. In somesolutions, the WTRU may determine or select an order (or sequence) forthe transmission of HARQ-ACK bits in a subframe. The selection of anappropriate order may enhance decoding performance of HARQ-ACK at thenetwork side by avoiding those HARQ-ACK bits that are known by thenetwork to be NACK (e.g., because they correspond to cells/subframewhere PDSCH was not transmitted) that are in consecutive positions ofthe codebook.

The order may be selected based on an indication from downlink controlsignaling (such as a codebook indication or a shuffling indication).Alternatively, the order may be determined based on the set of PDSCHreceived or not received in cells and/or subframes for which HARQ-ACK isto be reported. Further, the order may be dependent on the total size ofthe HARQ-ACK codebook in a particular subframe.

In some examples, the WTRU selects one of a number of possible codebookswhich may comprise the same number of bits but where the position ofeach bit corresponds to the ACK or NACK outcome of PDSCH for differentcells, subframes and/or transport blocks of a cell. For example, in afirst codebook the 23rd bit may correspond to the 1st transport blockreceived from the 12th configured cell, while in a second codebook the23rd bit may correspond to the 2nd transport block received from the18th configured cell. The total number of bits of each codebook may bedetermined based on the number of configured cells, the number oftransport blocks that can be received in each cell (depending on thetransmission mode) and the subframe configuration.

In some examples, a set of codebooks may be constructed frominterleaving or re-ordering bits from a base codebook whose bit order isdetermined based on pre-defined rules. For example, the base codebookorder may be first by order of transport block(s) within a cell, then byorder of subframe index (for TDD) second and lastly by order ofconfigured cells. Another possible rule for a base codebook may be firstby order of cells, then by order of subframe index (for TDD) and lastlyby order of transport blocks.

A specific codebook of the set may correspond to a defined permutationof the bits from the base codebook. A set of permutations may be definedexplicitly (e.g., using a Table) for each possible number of codebooksizes. For example, for a codebook size of 64 bits, 2 permutations maybe defined as [1; 2; 3; 4; 5; . . . 64] and [1; 33; 2; 34; 3; 35; . . .32; 64]. Alternatively, a set of permutations may be defined using aformula that may be dependent on the codebook size. The formula mayimplement a set of pseudo-random permutations, or a set of permutationswhere each permutation is characterized by a specific difference betweenconsecutive entries, for example.

The codebook to use in a given subframe may be indicated by downlinkcontrol signaling. For example, the codebook may be indicated in a fieldof a DCI or the set of DCI's containing downlink assignments for thePDSCH for which HARQ-ACK is being reported. In another example, thecodebook may be indicated in a field of a DCI used for providing dynamicscheduling information on the transmission of uplink control informationon the PUCCH or PUSCH. In case only two codebooks are defined, the fieldmay consist of a single bit, indicating whether the base codebook or thepermuted (or “shuffled”) codebook is to be used.

Alternatively, the codebook to use in a given subframe may be determinedsuch that a certain metric dependent on the set of received PDSCH isoptimized. For example, the codebook may be selected such that themaximum number of consecutive bits corresponding to A/N bits of thePDSCH that were not assigned (or not detected to be assigned) isminimized.

In some examples, the WTRU may not determine at least one property ofthe codebook based on the received downlink assignments, such that therewould be certainty that it matches with the codebook assumed at thenetwork side. In such a situation the codebook may be considered“undetermined” by the WTRU.

The WTRU may consider that the codebook is undetermined when one of thefollowing occurs: the WTRU did not receive at least one codebookindicator (or codebook size indicator) from the set of downlinkassignments; a field in the last received downlink assignment of apre-defined sequence of cells/carriers and subframes, indicates thatfurther downlink assignments should be received; the WTRU did notreceive at least one codebook indicator from the set of downlinkassignments for a subframe, where the codebook indicator indicates a setof cells, cell groups and/or transport blocks for this subframe only(possibly, only if a field received in the last subframe where adownlink assignment was received indicates that further downlinkassignments may be present in the next subframe(s)); the WTRU did notreceive at least one codebook indicator from the set of downlinkassignments for the last subframe, where the codebook indicatorindicates a set of cells, cell groups and/or transport blocks for allsubframes up to and including the subframe where it is received(possibly, only if a field received in a downlink assignment in the samesubframe as the last received codebook indicator indicates that furtherdownlink assignments may be present in the next subframe(s)); and/or theDAI-codebook is not consistent with the codebook indicator for at leastone portion of the codebook but cannot determine the correct size of thecodebook (e.g., if the indicator only indicates a range of sizes).

When the WTRU considers that the codebook is undetermined, the WTRU maytransmit HARQ-ACK using a default codebook defined from higher-layerconfiguration only; transmit an indication that the codebook isundetermined over a specific PUCCH resource and format or possibly overPUSCH if a PUSCH transmission is present (the specific PUCCH resourceand/or format may be configured by higher layers, or may be obtainedfrom downlink control signaling (e.g., ARI); the indication may consistof a single bit (e.g., corresponding to NACK) and may be multiplexedwith HARQ-ACK of the default codebook, if transmitted); and/or refrainfrom transmitting any HARQ-ACK in either PUCCH or PUSCH.

In an example, a transmission of HARQ feedback using multiple feedbackgroups may be used. In some solutions, the HARQ feedback informationthat needs to be transmitted in a given uplink subframe may berepresented by more than one set of information bits. Each such set maybe referred to as a “feedback group” herein.

A feedback group may be defined based on cells, cell groups and/orsubframes. For example, a first feedback group may include HARQ feedbackfrom a first group of cells (e.g., a first group of 8 configured cells),a second feedback group may include HARQ feedback from a second group ofcells (e.g., a second group of 8 configured cells), and so on.

In another example, a feedback group may be defined based on at leastone of: the total number of information bits that needs to betransmitted in the subframe based on at least semi-static information,and an order of such information bits; a maximum or target number ofinformation bits per feedback group; a maximum or target number offeedback groups; targeting an equal number of bits (or at most adifference of one bit) for each group; and minimizing the number offeedback groups. For example, in case the total number of informationbits to be transmitted in a subframe would be 36 and the maximum numberof information bits per feedback group would be 10, the feedback groupsmay consist of 4 groups of 9 bits.

In some solutions, the WTRU may encode and transmit information from afeedback group only if at least one PDSCH (or transport block)pertaining to this feedback group was received. In case at least onePDSCH was received for this feedback group, the WTRU may report “NACK”for cells and/or subframes from which PDSCH was not received and thatpertain to this feedback group. Alternatively, the WTRU may report“DTX”. For example, if a feedback group consists of HARQ feedback for agroup of 3 cells with two transport blocks per cell, and PDSCH wasreceived on the second cell only, there may be 6 information bits in thefeedback group. The two first and two last information bits(corresponding to the cell from which PDSCH was not received) mayindicate “NACK” while the two middle information bits (corresponding tothe cell from which PDSCH was received) may indicate “ACK” if thetransport block was decoded successfully and “NACK” otherwise.

In some solutions, the combinations of subsets of feedback groups may belimited to a set of valid combinations of feedback groups. For example,it may not be possible to transmit exactly one feedback group, such asgroup #2 only, but some combinations of 2 feedback groups may bepossible (such as #1 and #2). The WTRU may transmit information from afeedback group to obtain a valid combination of groups even if no PDSCHpertaining to this feedback group was received. The set of validcombinations may be pre-defined or provided by higher layers.

In an example, separate processing of transmitted feedback groups may beused. In a solution, the information bits of each feedback group forwhich transmission takes place may be separately encoded. For example,if a first feedback group consists of 8 bits and a second feedback groupconsists of 10 bits, each feedback group may be encoded into 24 codedbits (using, for instance, a Reed-Muller block code). Subsequentmodulation, spreading and mapping to physical resources may also beperformed separately for each feedback group.

The number of coded bits to use for each feedback group may be afunction of the number of bits of each feedback group. Each number ofcoded bits may be selected among a set of pre-determined values for thenumber of coded bits (such as 24 or 48). In some solutions, the selectednumber of coded bits may be selected to be the smallest number among thepre-determined values that achieves up to a maximum coding rate (e.g.,ratio of the number of information bits to number of coded bits).

In an example, joint processing of transmitted feedback groups may beused. In a solution, the information bits of each feedback group forwhich transmission takes place may be jointly processed and mapped to asingle resource. For example, there may be 4 defined feedback groups(labeled #1, #2, #3 and #4) consisting of 8, 12, 10 and 14 bitsrespectively. In a subframe where feedback groups #1, #3 and #4 aretransmitted, a total of B=32 bits (=8+10+14) may be encoded.

The encoding may consist of multiple Reed-Muller block codes where theset of B bits may be equally split into M subsets of up to N informationbits and where each subset is independently encoded. The coded bits fromthe M subsets may then be multiplexed prior to subsequent processing(which possibly includes modulation, spreading and mapping to physicalresources). Such type of encoding may improve performance at thereceiver by reducing the total number of codeword candidates to betested. The number M of subsets may be a function of the number B ofbits according to a pre-defined function. For example, M may be set tothe smallest integer larger than the ratio B/N.

In another example, the encoding may use other types of codes such asconvolutional or turbo encoding. The type of encoding used in a specificsubframe may be a function of the number B of bits to be transmittedgiven the subset of feedback groups for which transmission takes place.For example, in a subframe where the subset of feedback groups resultsin B<=B0 bits to be transmitted (where B0 could be a fixed value such as40), the WTRU may use multiple Reed-Muller block codes. In a subframewhere B is larger than B0 but smaller or equal than B1 (where B1 couldbe a fixed value such as 100), the WTRU may use convolutional encoding.In a subframe where B is larger than B1 the WTRU may use turbo encoding.

A set of CRC bits may be appended to the set of B bits prior to encodingto improve reliability. The number of CRC bits may depend on the numberof bits B, or may depend on the type of encoding applied. For example,zero (0) CRC bits may be appended when B is smaller or equal than B0bits, or when convolutional or turbo encoding is not used.

FIG. 5 is a diagram of an example selection process for channel codingand inclusion of CRC based on the number of feedback bits to betransmitted. As shown in process 500, the WTRU may receive a pluralityof transport blocks over a set of a plurality of configured carriers 510and generate HARQ-ACK feedback 520 for the plurality of transportblocks. The inclusion of HARQ-ACK feedback for a carrier may be based ona DAI field present in a downlink assignment for that carrier. Further,supplemental HARQ-ACK feedback bits may be inserted in the HARQ-ACKCodebook, depending on the value of successive DAIs detected by theWTRU. Further, there may be no downlink assignment for a carrier. TheHARQ-ACK feedback 520 may use HARQ-ACK feedback bits 525. The WTRU maydetermine the number of HARQ-ACK feedback bits used. The WTRU maycompare the number of HARQ-ACK feedback bits, which may be representedby n, to a threshold, such as threshold B 530. In an example, if thenumber of feedback bits is less than or equal to the threshold andtherefore n≤B, then Reed-Muller coding may be used 540. The set ofencoded feedback bits 545 may result from the Reed-Muller coding.Further, if the number of feedback bits is greater than the thresholdand therefore n>B, then the WTRU may insert or append CRC 550. Also, ifthe number of feedback bits is greater than the threshold and thereforen>B, then the WTRU may use convolutional coding 560. The set of encodedfeedback bits 565 may result from the convolutional coding.

In some solutions, a finite set of possible number of information bitsB′ (or payload sizes) prior to encoding may be allowed to simplifydecoding at the receiver. This set may be pre-defined or be determinedfrom the configuration (such as the number of cells, groups of cells,number of transport blocks per cell, and so on). The specific payloadsize B′ to use in a specific subframe may also be determined dynamicallyfrom downlink control signaling. For example, a field in a PDCCH/E-PDCCHmay indicate one of a set of possible payload sizes B′ that arepre-defined or configured by higher layers. In another example, a fieldmay indicate one of a set of possible PUCCH formats, each of whichcorresponding to a payload size depending on the configuration (numberof cells, cell groups, and so on). The WTRU may use padding bits whenthe number B of bits to transmit is lower than an allowed number ofinformation bits B′. For example, a set of possible payload sizes may be20 bits, 50 bits and 100 bits. In case the number of bits to betransmitted B, based on a selected subset of feedback groups, would be60 bits, the WTRU may employ padding bits such that the total payload is100 bits. The WTRU may also transmit information from additionalfeedback groups (not initially selected) such that the total number ofbits matches a valid payload size.

The number of coded bits to use may be a function of the total number ofbits B or the payload size B′. It may be selected among a set ofpre-determined values for the number of coded bits. In some solutions,the selected number of coded bits may be selected to be the smallestnumber among the pre-determined values that achieves up to a maximumcoding rate (i.e., the ratio of the number of information bits to numberof coded bits).

In an example, a determination of a resource may be used. As describedherein, a resource may refer to a set of transmission properties for thetransmission of feedback (e.g., over PUCCH). The resource may beidentified by an index from which all properties are derived, such as aset of RBs, properties of one or more DM-RS sequence(s), at least onespreading sequence, and the like. In case PUCCH is configured onmultiple cells, a resource may include the cell on which PUCCH is to betransmitted, or a set of cells. A sub-resource may refer to a portion ofsuch resource—for example, one RB in case the resource consists of a setof more than one RB, or one spreading sequence in case the resourceconsists of a set of more than one spreading sequence, or one cell incase the resource consists of multiple cells.

The WTRU may determine the resource or sub-resource used for thetransmission of a feedback group, or a combination of feedback groups,based on downlink control signaling that may be associated with at leastone of the PDSCH pertaining to the feedback group. For example, theresource or sub-resource may be indicated by an ARI field in aPDCCH/E-PDCCH scheduling a PDSCH pertaining to the feedback group or toa feedback group part of the combination. In another example, theresource or sub-resource may depend on the cell or cell group from whichthe PDCCH/E-PDCCH is decoded, or the cell or cell group of acorresponding PDSCH. For example, the cell on which PUCCH is transmittedmay be the cell in the same cell group as the cell group from whichPDCCH/E-PDCCH is decoded. In another example, signaling such asdescribed herein may be used.

The resource used for the transmission of a combination of feedbackgroups may depend on the number of coded bits and/or associated PUCCHformat, possibly in combination with an ARI. For example, the WTRU mayselect a first resource if the number of coded bits is a first numberand the received ARI is a first value, and a second resource if thenumber of coded bits is a second number and the received ARI is a firstvalue. The mapping between the resource and a combination of ARI andnumber of coded bits may be configured by higher layers. In anotherexample, the WTRU may be configured with a single resource for eachPUCCH format or for each possible number of information bits or codedbits. In this case, the WTRU may select the PUCCH resource correspondingto the number of information bits or coded bits that needs to betransmitted (or the PUCCH format that needs to be used).

In an example, fixed mapping of a feedback group to a sub-resource withpossible zero-power transmission may be used. The WTRU may determine theresource or sub-resource used for the transmission of a feedback group(or a combination of feedback groups) based on a combination of downlinkcontrol signaling that may be associated with any PDSCH and of an indexor order associated with this feedback group. For example, thecombination of an index received from an ARI field and of an index tothe feedback group may determine the resource or sub-resource for thetransmission of this feedback group. For example, a specific value ofARI may indicate a resource spanning two (2) contiguous RBs, and theremay be two feedback groups to be transmitted. In this case thesub-resource used for the first feedback group may be the first of thetwo RBs, and the sub-resource used for the second feedback group may bethe second of the two RBs.

In case no transmission needs to take place for a feedback group, theWTRU may transmit with zero power (i.e., may not transmit) on thecorresponding sub-resource. In some solutions, the WTRU may transmit ona sub-resource even if no transmission needs to take place for thecorresponding feedback group to ensure that the signal transmitted bythe WTRU spans contiguous RBs. The WTRU may perform such transmission,for instance, if the sub-resource is over a RB and non-zero-powertransmission takes place on both adjacent RBs. In this case, the WTRUmay encode the information for the corresponding feedback groupaccording to a pre-determined rule, for instance as if the WTRU reports“NACK” or “DTX” for all corresponding transmissions of the feedbackgroup.

In an example, flexible mapping of a feedback group to a resource with apossible indication may be used. The resource used for the transmissionof a specific feedback group may also be determined based on the subset(or combination) of feedback groups that are transmitted in thesubframe. This solution may ensure that the combination of resourcesused for the transmission of all feedback groups results in a signalwith desirable properties, such as a signal which spans contiguousresource blocks. For example, there may be 4 defined feedback groups(labeled #1, #2, #3 and #4) and the value received from downlink controlsignaling (e.g., ARI) may determine a set of resources spanning 4contiguous resource blocks (labeled #a, #b, #c and #d). When all 4feedback groups are transmitted, groups #1, #2, #3 and #4 may be mappedto resources #a, #b, #c and #d respectively. On the other hand, if onlygroups #1, #2 and #4 are transmitted, these groups may be mapped toresources #a, #b and #c such that only contiguous resource blocks areused. When there is possible ambiguity for the network on the identityof the feedback group transmitted on a given resource, the WTRU mayinclude an indication of the feedback group in at least this resource,such as a bit indicating whether the feedback group transmitted overresource #c is #3 or #4. Such indication may be jointly or separatelyencoded with the information bits from the feedback group.

In an example, a transmission of a feedback group indicator may beperformed. In some solutions, the WTRU may transmit at least oneindication of the subset of feedback groups transmitted in a subframe tofacilitate decoding at the receiver. Such indication may be referred toas “feedback group indication” (FGI) in the following. A value of FGImay indicate one of a set of valid possible combinations of feedbackgroups, including a codebook size. The mapping between each possible FGIvalue and a combination of feedback groups may be provided by higherlayers or pre-defined. The mapping may be dependent on the total numberof information bits B, and/or the payload size B′ for the transmissionin the subframe. In some solutions the FGI may consist of an indicationof a transmission format for PUCCH.

In a solution, a FGI may be processed separately from other feedbackbits and mapped to specific physical resources. For example, FGI bitsmay be encoded, modulated, spread and mapped to specific sub-carriersand/or slots of a resource block. This solution has the benefit thatmultiple possible numbers of information bits (B) may be supportedwithout excessively increasing complexity at the receiver, since thereceiver can first determine the number of information bits by firstdecoding the FGI.

In a solution, FGI bits may be concatenated to other feedback bits (andpossibly interleaved) prior to subsequent joint processing (possiblyincluding at least one of coding, modulation, spreading and mapping tophysical resources). This solution may be particularly beneficial if thepossible set of payload size(s) is known at the receiver.

In a solution, FGI bits may be used to mask a CRC appended to the set offeedback bits. This solution has the benefit of providing increasedreliability through error detection while at the same time reducing thepossibility of error in the feedback transmission due to missed PDSCHassignments or falsely detected PDSCH assignments. At the receiver, thenetwork may attempt decoding assuming a given payload size (or a set ofpossible payload sizes) and checking if the CRC masked by the expectedFGI value given the transmitted PDSCH is valid.

In a solution, the resource used for the transmission of feedback may bea function of the FGI, possibly in combination with information receivedfrom downlink control signaling (such as ARI) and higher layers. Thissolution provides an implicit FGI signaling mechanism since the receivercan determine the FGI from the resource from which the feedbackinformation could be decoded.

In an example, power setting may be used. The WTRU may determine thepower to apply for a transmission containing feedback information(including a transmission only containing feedback information, such asa PUCCH transmission) based on at least a path loss estimate PL_(c), aconfigured maximum power P_(CMAX,c), parameters provided by higherlayers such as P_(0_PUCCH), Delta_(F_PUCCH) and Delta_(TxD), a parameterdependent on received TPC commands g(i) and/or a power offset h that isa function of parameters that may change on a subframe basis asdescribed in the following.

In some solutions, a power offset may be a function of at least one of:a total number of information bits B based on the subset of feedbackgroups selected for transmission, possibly including feedback groupstransmitted to ensure transmission over contiguous RBs; the largestnumber of information bits of a feedback group among a subset selectedfor transmission; a number of transport blocks based on received PDSCH;a number of transport blocks based on received PDSCH in each feedbackgroup, or the maximum thereof among feedback groups; a maximum number oftransport blocks that may be received based on configuration; a payloadsize B′ for the transmission of feedback information in the subframe;the type of coding employed in the subframe (Reed-Muller, convolutional,turbo); whether CRC and/or FGI is appended to the set of transmittedfeedback bits; a number of subsets M of bits independently encoded priorto multiplexing; and a number of bits transmitted in each subset ofindependently encoded bits, or the maximum thereof among all subsets,where the number of bits may or may not be restricted to thosecorresponding to received PDSCH.

The power offset function may depend on different parameters dependingon the type of coding that is being utilized, or more generallydepending on the transmission format being used. For example, in casecoding is based on a block code such as Reed-Muller, the power offsetmay be a function of the number of transport blocks based on receivedPDSCH in the subframe, or perhaps the maximum number thereof amongindependently encoded subsets. On the other hand, in case coding isbased on a convolutional code or a turbo code, the power offset may be afunction of the maximum number of transport blocks that may be receivedbased on configuration. This solution may be appropriate since, in caseblock coding based on small codebooks is used, the receiver can utilizethe knowledge of information bits that are known to be set to NACK(based on scheduled PDSCH) to improve the likelihood of correctdetection.

In legacy systems, the number of coded modulation symbols per layer Q′for HARQ-ACK may be set to a value proportional to the number ofinformation bits for HARQ-ACK, the number of sub-carriers of the initialPUSCH transmission and a factor β_(offset) ^(HARQ-ACK), but not largerthan 4 times the number of sub-carriers of the PUSCH. Coding,interleaving, multiplexing and mapping of higher layer data is performedindependently of the presence or absence of HARQ-ACK. When HARQ-ACK istransmitted, its coded modulation symbols may overwrite the symbols usedfor higher layer data in certain resource elements, resulting in modestperformance degradation for higher layer data due to puncturing.

When a large number of HARQ-ACK bits need to be transmitted, it may bepossible that the limit of 4 times the number of sub-carriers of thePUSCH becomes insufficient, for example in power-limited scenarios whereit may not be possible to have very large bandwidth for PUSCH. In somesolutions, the limit of 4 times the number of sub-carriers of the PUSCHallocation may be lifted such that modulation symbols for HARQ-ACK maybe mapped to additional resources (for example, time symbols) on PUSCH.

In some solutions, to prevent performance degradation due to excessivepuncturing, the WTRU may process higher layer data taking into accountthat at least some resource elements are not available for higher datadue to the transmission of HARQ-ACK, or of a minimum number of bitsthereof. More specifically, the following parameters or procedures maybe affected. The transport block size of the higher layer data may beaffected. For example, the calculation of the transport block size as afunction of the signaled modulation and coding scheme (MCS) and of thesize of the PUSCH allocation (in resource blocks) may take into accounta number of time symbols that are not available due to the transmissionof HARQ-ACK. For example, in case the number of modulation symbolsrequired for HARQ-ACK exceeds 4 times the number of subcarriers of thePUSCH, the transport block size may be scaled down by a factor(12−4)/12=⅔ to take into account the fact that at least ⅓ of the timesymbols (not used for DM-RS) are not available for higher-layer datawhen HARQ-ACK may need to be transmitted. The procedure of mapping toREs for PUSCH may be changed such that a subset or all of the REs onwhich symbols for HARQ-ACK are mapped are excluded from the set of REson which symbols for PUSCH may be mapped. For example, the REs on the 4first time symbols on which symbols for HARQ-ACK may be mapped may beexcluded.

The WTRU may determine that higher layer data is processed according tothe above based on at least one of the following conditions. The WTRUmay determine higher layer data is processed according to explicitsignaling from a received PDCCH/E-PDCCH. The received PDCCH/E-PDCCH maybe the PDCCH/E-PDCCH containing the uplink grant for the concerned PUSCHtransmission, or another received PDCCH/E-PDCCH possibly indicatinginformation about a set of PDSCH and/or PUSCH transmissions. A new orexisting field of a DCI may be used for this purpose. This solution hasthe benefit of robustness against the loss of downlink assignments. TheWTRU may determine higher layer data is processed according the numberof HARQ-ACK information bits to be transmitted in the PUSCH. The WTRUmay also determine higher layer data is processed according to whetherthe number of symbols for HARQ-ACK exceeds a threshold, such as 4 timesthe number of sub-carriers of the PUSCH transmission.

In an example, a WTRU may select an uplink resource for UCItransmission. In examples, the WTRU may determine a resource fortransmission UCI in the following situations: possibly multiple types ofphysical channels available for transmission of UCI, e.g., both PUSCHand PUCCH; possibly multiple types of UCI available for transmission,e.g., HARQ-ACK, CSI or SR; and/or possibly some cells on carriersoperating in an unlicensed frequency band (for example, LAA).

In an example, a WTRU may split UCI across PUSCH and PUCCH. In oneexample method, the WTRU may determine that a first amount of UCI may beapplicable to a first type of transmission, e.g., PUCCH while a secondamount may be applicable to a second type of transmission (e.g., PUSCH).Possibly, such method may be applicable per group of cells e.g., for aPUCCH group or for a cell group (e.g., a CG).

For example, the first amount of UCI may correspond to a specific typeof UCI e.g., HARQ A/N bits. For example, the second amount of UCI maycorrespond to other type of UCI e.g., CSI such as CQI, precoding matrixindicators (PMI) or RI bits.

In a subframe in which the WTRU is expected to transmit UCI, the WTRUmay determine whether or not at least one PUSCH resource is availablefor the concerned subframe. The WTRU may also determine whether or notit is configured for simultaneous transmissions on PUCCH and PUSCH for agiven serving cell or group of cells.

If the WTRU may perform transmission simultaneously on PUSCH and PUCCH(e.g., resources are available and the WTRU is configured for suchoperation), the WTRU may determine that a first type of the UCI e.g.,HARQ-ACK may be transmitted on a PUSCH transmission while the secondtype of UCI e.g., the CSI may be transmitted on a PUCCH transmission, orvice-versa. The WTRU may also determine that a first portion of a giventype of UCI (e.g., HARQ-ACK) may be transmitted on a PUSCH transmissionwhile a second portion may be transmitted on a PUCCH transmission.according to at least one of the following: reception of downlinkcontrol signaling e.g., using similar methods as described herein (suchsignaling may indicate that UCI shall be split using the PUSCH and PUCCHtransmissions); reception of downlink control signaling, e.g., usingsimilar methods as described herein (such signaling may include a UCIrequest where the indicated UCI may be routed to a first specificresource and/or transmission (e.g., PUCCH, or possibly the resourceindicated by dynamic scheduling, e.g., according to that describedherein) while other feedback may be routed to a second specific resourceand/or transmission (e.g., PUSCH, or possibly dropped), or vice-versa);the PUSCH allocation (e.g., the size of the grant) is smaller (or equalto) a (possibly configurable) threshold; the resulting ratio of thenumber of (non-UCI) payload bits and the number of UCI bits for theconcerned PUSCH transmission is equal or higher than a specificthreshold for the concerned amount of UCI bits; the resulting ratio ofthe number (non-UCI) payload bits and the number of HARQ A/N bits forthe concerned PUSCH transmission is equal or higher than a specificthreshold; the number of modulation symbols Q′ per layer for a UCI typeand the concerned PUSCH transmission would exceed a threshold (forexample, the threshold may be 4 times the number of sub-carriers of thePUSCH in case of HARQ-ACK).

When at least one of the above conditions is met, the WTRU may determinethe portion of UCI bits transmitted on each channel according to atleast one of the following. The WTRU may determine the portion accordingto information including a first type of UCI (e.g., the HARQ ACK bits)in the concerned PUSCH transmission up to the required number of symbolsfor the concerned UCI. The WTRU may transmit remaining UCI (e.g., of thesecond type e.g., the CSI bits) using a transmission on PUCCH. Also, theWTRU may determine the portion according to information including anumber of UCI bits in the PUSCH transmission based on the PUSCHallocation (e.g., the size of the grant); the remaining UCI bits maythen be transmitted using a different transmission. For example, theWTRU may determine a number of HARQ-ACK bits which would results in anumber of modulation symbols Q′ per layer no larger than a thresholdthat may be dependent on the size of the PUSCH, such as N times thenumber of sub-carriers. In another example, the number of UCI bits inthe PUSCH transmission (possibly of a given type) may be set to zero andall bits may be transmitted over a different transmission.

In an example, a WTRU may split UCI across multiple PUCCHs. In oneexample method, the WTRU may determine that a first amount of UCI may beapplicable to a first type of transmission, e.g., PUCCH on the resourcesof a first serving cell (e.g., the PCell) while a second amount may beapplicable to a first type of transmission (e.g., PUCCH) on theresources of a second serving cell (e.g., SCell configured with PUCCH).Possibly, such method may be applicable per group of cells e.g., for aPUCCH group or for a cell group (e.g., a CG), or across PUCCH groups orCGs.

For example, the first amount of UCI may correspond to a specific typeof UCI e.g., HARQ A/N bits. For example, the second amount of UCI maycorrespond to other type of UCI e.g., CSI such as CQI, PMI or RI bits.In such case, the WTRU may determine the cell with PUCCH on which totransmit a first UCI type according to at least one of the following:reception of downlink control signaling e.g., using similar methods asdescribed herein (such signaling may indicate that UCI shall be splitusing the different PUCCH transmissions and that the first type of UCIis to be transmitted using resources of a specific cell (e.g., the cellon which the control signaling has been received)); reception ofdownlink control signaling, e.g., using similar methods as describedherein (such signaling may include a UCI request where the indicated UCImay be routed to a first specific PUCCH resource and/or PUCCHtransmission (e.g., possibly the resource indicated by dynamicscheduling, e.g., as described herein) while other feedback may berouted to a second specific PUCCH resource and/or PUCCH transmission(e.g., according to other methods to determine a PUCCH resource), orvice-versa); the PCell always (or the PSCell if for the MCG) or,alternatively, the SCell always; the WTRU selects the PUCCH withsufficient capacity (and/or with the best expected transmissionperformance); the WTRU selects the cell for which it has the lowestpathloss estimate; the WTRU selects the cell for which it also hasresources for a PUSCH transmission (only if simultaneous PUSCH+PUCCHtransmission is configured for the WTRU); and according to a semi-staticconfiguration.

In an example, a WTRU may select a single PUCCH when multiple areavailable. In a possible example, a WTRU may select a single PUCCH whenmultiple are available only if the WTRU may perform transmission ondifferent PUCCHs simultaneously. In another example, the WTRU may selectthe serving cell with the PUCCH according to at least one of thefollowing: the WTRU selects the cell based on received control signalingsimilar to the above; reception of downlink control signaling, e.g.,using similar methods as described herein, (such signaling may includedynamic scheduling for UCI transmission, e.g., according to thatdescribed herein); the WTRU selects the PUCCH with sufficient capacity(and/or with the best expected transmission performance); the WTRUselects the cell for which it has the lowest pathloss estimate; andaccording to a semi-static configuration. In several examples, the WTRUmay only consider cells in the activated state.

The WTRU may be configured with a plurality of PUCCH resources on atleast one SCell. Possibly, the WTRU may be configured with a restrictionon the number of simultaneous uplink transmissions it may perform. Suchrestriction may be for all transmissions of the WTRU (e.g., includingall transmission for all configured cells or CGs), for all transmissionof a given CG of the WTRU's configuration, for all physicaltransmissions of a specific type (e.g., only for PUCCH transmission)and/or for all transmission of a certain type (e.g., only for UCItransmissions).

In such case, the WTRU may determine what uplink transmission it may usefor the transmission of UCI according to solutions described herein. Inan example, a WTRU may determine uplink routing as a function ofrestrictions.

In one method, the WTRU may determine how to route transmission of UCIas a function of restrictions applicable to the number of simultaneousuplink transmissions (and, possibly, only for simultaneous PUCCHtransmissions). For example, the WTRU may determine that transmission ofat least some of the UCI should be performed in a given subframeaccording (and possibly for a given CG) to at least one of thefollowing: the WTRU may perform at most a number X of transmission onPUCCH (for example, the WTRU may determine the applicable X number ofserving cells with PUCCH resources according to at least one of thefollowing: in decreasing order of required transmit power for the PUCCHtransmission; in increasing order of the estimated pathloss referencefor the corresponding carrier; and in decreasing order of the PUCCHcapacity); and the WTRU may perform at most a number X of transmissionon PUCCH for a given group of cells (e.g., at most one PUCCHtransmission per PUCCH group if a group may be configured using morethan one PUCCH resource. The WTRU may use similar methods as for theprevious case possibly applied per group of cells).

The WTRU may be configured with at least one serving cell using acarrier that is operating in an unlicensed frequency band (hereafter“LAA-Cell”). The following solutions describe how the WTRU may determinewhat uplink resource to use for the transmission of at least some (orall) of the generated UCI as a function of the type of access, type ofband (e.g., licensed or unlicensed), the type of UCI itself (e.g., HARQA/N, CQI, PMI/RI or the like) and/or received control signaling (e.g.,similar as the signaling aspects described herein).

In an example, such as an example method, the WTRU may route UCI onresources of a serving cell of a licensed band. The WTRU may determinethat the applicable UCI may be transmitted using uplink resources of aserving cell of the WTRU's configuration associated with a carrier in afrequency band used for licensed operation. The WTRU may make suchdetermination independently of whether or not the WTRU has an uplinktransmission scheduled for uplink resources of a LAA-Cell.Alternatively, the WTRU may transmit at least part of the UCI on a PUSCHtransmission of the LAA-Cell (if available) such that the WTRU may makesuch routing determination only when there is no PUSCH transmission forthe LAA-Cell.

Such applicable UCI may be determined according to at least one of thefollowing. The WTRU may not transmit any UCI using resources of aLAA-Cell. For example, the WTRU may route any UCI related to the LAAoperation to a transmission associated with a carrier in the licenseddomain independently of whether or not the WTRU has a resource for aPUSCH transmission for a LAA-Cell. In another example, the WTRU maytransmit only UCI associated with the LAA-Cell using resources of aLAA-Cell when available, otherwise the UCI may be routed to a resourceof a cell in the licensed domain. For example, the WTRU may route onlyUCI related to a LAA-Cell to a transmission on a resource of a LAA-Cell,if such transmission is available (e.g., a PUSCH transmission isscheduled). In a further example, the WTRU may perform any of the above,but only for the transmission of a specific type of UCI. For example,the WTRU may transmit (the more time-sensitive) HARQ A/N feedbackrelated to the operation in the unlicensed domain only using resourcesof a cell in the licensed domain; in such case, other type of UCI may betransmitted using a PUSCH transmission in the unlicensed domain (ifavailable) or using resources in the licensed domain (otherwise).

In a further example, applicable UCI may be determined by reception ofdownlink control signaling, e.g., using similar methods as describedherein. Such signaling may include a UCI request where the indicated UCImay be generated based on the status of the HARQ processes at the timeof the reception of the control signaling, e.g., the UCI may beassociated with the most recent state of the respective HARQ process(es)and not necessarily associated with transmissions receivedsimultaneously and/or during the time interval associated with thereception of such control signaling. In addition, the WTRU may receiveUCI scheduling information similar to that described herein for UCIfeedback associated with such a cell.

Methods are described herein for determination of uplink resources forUCI transmission. Methods are described herein such that the WTRU maydetermine, at least in part, what resource to use for at least some UCIbased in downlink control information, for example, dynamic scheduling.

Methods are described herein for downlink control signaling withDCI(UCI). In an example, the WTRU may receive dynamic schedulinginformation for the UCI. Such dynamic scheduling information may bereceived on PDCCH using DCI. Such scheduling information may be includedin an existing DCI format (e.g., using one of more indices to refer tospecific control information) or in a dedicated DCI format. Such DCI maybe further referred to herein as DCI(UCI).

Dynamic scheduling may include UCI request and/or resource allocation.Such DCI(UCI) may indicate at least one of: a UCI request (e.g., bywhich the WTRU may determine what UCI to include in a giventransmission); and UCI scheduling information (e.g., by which the WTRUmay determine what uplink resource and how to transmit applicable UCIusing the dynamically scheduled information.

In an example, DCI(UCI) may indicate a UCI request. A UCI request may beused to determine what UCI to generate for transmission. In an example,the WTRU may determine, as a function of the UCI request, what feedbackto include in a UCI transmission.

Further, a UCI request may be used to create a smaller UCI payload. Inan example, the UCI request may be used to prioritize transmission ofthe requested UCI and possibly to drop (or down-prioritize) other UCI.

Also, a UCI request may be used to route a subset of UCI to a specificresource, scheduled or not. In an example, the UCI request may be usedto assign the indicated UCI to a specific uplink resource, e.g., such asa resource indicated by the UCI scheduling information (if applicable,see examples herein).

A UCI request contents may include at least one of the followinginformation: a type of UCI, a serving cell identity, a downlink HARQprocess identity, a UCI size reduction method, a feedback group, andaperiodic requests. For example, the UCI request contents may include atype of UCI. The WTRU may determine what type of UCI in shall include inthe UCI transmission, e.g., HARQ A/N only or also in combination withany applicable CSI. For example, the type may be implicit to the formatof the DCI(UCI), e.g., based on the field arrangement in the DCI(UCI)format. For example, the DCI(UCI) format may include one field for a CSIrequest and one field for a HARQ A/N request (e.g., as separate bitmapfields).

In another example, the UCI request contents may include a serving cellidentity. The WTRU may determine the identity of the serving cell(s) forwhich the request is applicable, e.g., the request for the concerned UCImay be applicable to all configured (and/or also possibly active)serving cells of the WTRU's configuration, or to a subset thereof, e.g.,as indicated by the signaled identities.

For example, the identities may correspond to the serving cell identityconfigured by higher layer, to cells that are part of a group of cells(e.g., based on a configured grouping, based on grouping for PUCCHtransmission—PUCCH group, based on Timing Advance Grouping (TAGs), onlyfor a special cell—e.g., PCell of MCG or PSCell of SCG, or the like).Such identity may be based on the Carrier Field Indicator (CFI) used forcross-carrier scheduling.

In an example, the UCI request may indicate CSI only for subset of cellson a dynamically scheduled PUSCH, HARQ per legacy. For example, the UCIrequest may indicate that only CSI for a subset of serving cells isbeing requested e.g., for serving cell IDs 1 and 3. Such indication maybe received using a bitmap arrangement similar to the example shown inTable 9. The WTRU may then include CSI for those cells with theapplicable UCI for the uplink transmission.

The WTRU may perform such uplink transmission, e.g., using dynamicscheduling (e.g., possibly on PUSCH). In an example, such UCI requestsignaling for CSI may be only applicable to periodic CSI (e.g., periodicCQI reporting) or, preferably, for any type of CSI including aperiodicCSI. Table 9 is an example of a bitmap arrangement for a CSI feedbackrequest.

TABLE 9 0 1 2 3 4 5 6 7 ServCellID 0 1 0 1 0 0 0 0 Report CSI

In a further example, the UCI request contents may include a downlinkHARQ process identity. The WTRU may determine the identity of the HARQprocess(es) for which the request is applicable, e.g., when the type ofUCI requested is HARQ feedback. For example, the control information mayuse, e.g., a bitmap representation of all HARQ processes of the WTRU ina specific order for each (and also possibly activated) cell of theWTRU's configuration, e.g., increasing order of the process ID for allapplicable cells in increasing order, e.g., based on their respectiveserving cell identity. Table 10 is an example of a bitmap arrangementfor a HARQ feedback request.

TABLE 10 0 1 2 3 4 5 6 7 HARQ Process ID 0 1 0 1 0 0 0 1 ServCellID = 01 0 0 0 1 0 0 0 ServCellID = 1 0 0 0 0 0 0 0 0 ServCellID = 2 1 0 1 1 11 0 0 ServCellID = 3

In an example, HARQ feedback may be included only for specific processesfor all applicable cells. For example, the WTRU may determine from thereception of a UCI request that it shall include HARQ feedback forprocesses x1, x3 and x7 for serving cell ID=0, x0 and x4 for servingcell ID=1 and x0, x2 , x3, x4 and x5 for serving cell ID=3 as shown inTable 10. In such case, the WTRU may generate 10 bits of HARQ feedbackfor transmission on an uplink resource. The WTRU may then determine theapplicable coding and the applicable uplink resource using any of themethods described herein or using legacy methods.

In an example, an overload may indicate the presence or absence ofdynamic scheduling information for the processes. In an example, theHARQ feedback may correspond only to transmissions for which the WTRUhas scheduling information (e.g., dynamic and/orconfigured/semi-persistent) such that the request may also indicate thatthe concerned processes have been scheduled. In such case, the WTRU mayperform a verification to determine if (and possibly also for whatserving cell) the WTRU has failed to successfully decode one (or more)PDCCH(s) for the concerned interval (e.g., “missed PDCCH”), if it hasincorrectly decoded one (or more) PDCCH(s) successfully (e.g., “falsepositive”).

In an example, a special case may be used for configured DL assignments.For a HARQ process configured with a downlink assignment for theconcerned interval, the WTRU may determine that the UCI is alwaysrequested: in this case, the absence of a request for the concerned HARQprocess may indicate that no dynamic scheduling was associated with theprocess while the presence of such request may additionally indicatethat dynamic scheduling was associated with the process.

In an example, an overload may be used as PDCCH decoding help. In anexample, the WTRU may determine that UCI request corresponds to allcells of the WTRU's configuration (and possible, activated cells only)and/or for all such cells associated with such control signaling, suchthat the WTRU may use the UCI-request information to perform decodingattempts only for cells for which HARQ feedback is requested.

In another example, a HARQ feedback request may be independent of DLscheduling, e.g., state of process. In an example, the HARQ feedback maycorrespond to the state of the concerned HARQ process(es) independentlyof the scheduling activity for the concerned process(es). In such case,no further verification may be performed by the WTRU regarding detectionof missed PDCCH(s) and/or the possible occurrence of any false positive.

In a further example, the UCI request contents may include a UCI sizereduction method. In an example, the WTRU may additionally determinewhat size reduction method to apply to the requested UCI, e.g., anyother method described herein. For example, the UCI request may indicatethat for cells for which HARQ A/N is to be reported, the WTRU should usebundling for HARQ A/N for cells configured with spatial multiplexing(e.g., multiple transport blocks per interval).

In yet a further example, the UCI request contents may include afeedback group, for example, as described herein. In an example, theWTRU may determine the set of PDSCH transmissions and/or HARQ processesfor which it should provide feedback based on a dynamic feedback requestfield. Different codepoints of the field may map to different feedbackgroups (e.g., sets of PDSCH transmissions and/or HARQ processes) andthese codepoint mappings may be configured semi-statically, possibly byRRC configuration.

In yet another example, the UCI request contents may include aperiodicrequests. In an example, the WTRU may additionally determine from theUCI request that aperiodic uplink feedback should be sent.

The WTRU may implement additional behavior for HARQ A/N generated fromthe reception of one or more DCI(s) that activate or deactivate aconfigured downlink assignment and/or a configured uplink grant. In onemethod, the WTRU may always generate HARQ A/N report for such signalingindependently of the UCI request. In one method, the WTRU may generateHARQ A/N report for such signaling if the serving cell on which the WTRUreceived the control signaling is included in the UCI request (e.g., letthe network coordinate transmission of semi-persistent scheduling (SPS)commands and UCI requests coherently).

In another example, the WTRU may determine that the UCI indicated, e.g.,using methods described herein, is not to be generated and/or not to beincluded in an uplink transmission. In other words, such signaling maybe used to subdue some (or all) of the applicable UCI instead of beingconsidered as a UCI request.

In an example, DCI(UCI) may indicate scheduling information for UCI. AUCI request may be used to determine what UCI to generate fortransmission. In an example, the WTRU may determine, as a function ofthe UCI scheduling information, some or all the properties of the uplinktransmission for at least some of the applicable UCI, e.g., possiblyincluding the applicable transmission resources and/or the applicabletransmission format (including one of modulation, (starting) resourceblock(s), number of resource blocks, spreading, spatial multiplexing,possibly timing and/or timing offset, one or more DM-RS sequence, or thelike).

UCI scheduling information may include at least one of the followinginformation: a physical channel type (PUCCH, PUSCH), physical channeltype identity (e.g., PUCCH on PCell, PUCCH on SCell), serving cellidentity, PUCCH/UCI feedback group identity, PUCCH format, PUSCHtransmission parameters, PUCCH transmission parameters, channel coding,payload size, TPC command (power control information), and CSI request.Further, different combinations of the above scheduling information arepossible, such as depending on whether the indicated resource is a PUSCHresource or a PUCCH resource.

UCI scheduling information may include a physical channel type (PUCCH,PUSCH). The WTRU may determine what type of physical channel to use forthe transmission of UCI as a function of an indication inside thescheduling information. When no such indication is present, the WTRU maydetermine to use the PUCCH. When PUSCH is scheduled for transmission ofUCI (possibly only), the WTRU may not perform any WTRU-autonomousretransmission for the concerned HARQ process.

UCI scheduling information may include a physical channel type identity(e.g., PUCCH on PCell, PUCCH on SCell). The WTRU may determine whatphysical channel of a certain type (e.g., PUCCH) to use for thetransmission of UCI as a function of an indication (e.g., PUCCH onPCell, PUCCH on SCell) inside the scheduling information. When no suchindication is present, the WTRU may determine to use a default PUCCHchannel e.g., PUCCH on PCell. This may be applicable also to thetransmission of feedback on PUSCH, e.g., when the PUSCH of the servingcell configured with PUCCH may be scheduled for UCI transmission.

UCI scheduling information may include a serving cell identity. The WTRUmay determine the identity of the serving cell corresponding to thephysical uplink resource. Serving cell identity, or CFI, may be used forPUSCH scheduling for UCI. For example, the WTRU may receive a value thatcorresponds to an identity of a serving cell. Such identity may be basedon the serving cell identity used by other layers, e.g., servCell-ID inRRC. Alternatively, such identity may be based on a configured value forcross-carrier scheduling, e.g., a CFI. In an example, this may beapplicable when the scheduling information may indicate resources on aPUSCH.

UCI scheduling information may include a PUCCH/UCI feedback groupidentity. The WTRU may determine the identity of the uplink feedbackchannel corresponding to the physical uplink resource as a function ofan identity of a group of cells associated with a single uplink channel(e.g., a PUCCH group). This may be applicable also to the transmissionof feedback on PUSCH, e.g., when the PUSCH of the serving cellconfigured with PUCCH may be scheduled for UCI transmission.

UCI scheduling information may include a PUCCH format. The WTRU mayreceive an indication of the PUCCH format to use inside the schedulinginformation, e.g., PUCCH format 3 or other formats.

UCI scheduling information may include PUSCH transmission parameters.The WTRU may receive similar information as for a grant for an uplinkPUSCH transmission for the transmission on UCI feedback. In an example,such grant may be only for transmission of UCI.

UCI scheduling information may include PUCCH transmission parameters.The PUCCH transmission parameters may be similar to the parameters thatthe WTRU determines for existing PUCCH formats, e.g., PRB allocation.

UCI scheduling information may include channel coding. The WTRU maydetermine whether it should transmit one or a specific combination ofUCI type as a function of the indicated channel coding method.

UCI scheduling information may include payload size. The WTRU maydetermine the amount of UCI to include in the uplink transmission as afunction of the indicated payload size for the scheduled UCItransmission. In an example, if such information is absent, the WTRU mayuse any other methods such as those described herein and include the UCIrequest as described herein.

UCI scheduling information may include a TPC command (power controlinformation). This TPC command may be similar to the legacy TPC commandbut may be interpreted as a function of whether the schedulinginformation is for PUSCH or a PUCCH transmission.

UCI scheduling information may include a CSI request. This CSI requestmay be similar to the legacy request. In an example, such a CSI requestmay override other CSI reporting for the concerned time interval (e.g.,periodic CSI).

Further, different combinations of the above scheduling information ispossible as part of PUCCH or PUSCH. For example, the WTRU may receive aDCI(UCI) that schedules transmission of UCI on PUSCH which DCI(UCI) mayinclude the type of physical channel (i.e., PUSCH), the identity of theserving cell for the uplink transmission (e.g., serving cell 0—PCell),PUSCH transmission parameters, e.g., including a resource blockassignment, a modulation and coding scheme (MCS) and a TPC.

For example, the WTRU may receive a DCI(UCI) that schedules transmissionof UCI on PUCCH of the PCell which DCI(UCI) may include the type ofphysical channel (i.e., PUCCH), PUCCH transmission parameters, e.g.,including a resource block assignment, and a TPC. Additionally, theDCI(UCI) may include a UCI request such that the WTRU determines whatUCI to include in such transmissions. The WTRU may determine that thePUCCH of the PCell is being scheduled based on the identity of the cellon which the PDCCH for the DCI(UCI) was received.

In an example, DCI for UCI, or DCI(UCI) may be used. In an example, adedicated DCI may be used. In another example, extensions to existingDCIs may be used.

In an example, DCI(UCI) may indicate any of the information describedherein using a dedicated format that includes one (or more) field(s) forany of the aspects described herein or using one (or more) ind(ex/ices)inside the DCI(UCI) format.

In an example, no HARQ A/N may be generated by DCI, if transient. In anexample, the WTRU may receive DCI(UCI). The WTRU may not generate and/orinclude any HARQ A/N to report feedback for the DCI itself. The WTRU maynot do so if such DCI(UCI) is applied per subframe and/or per TTI.

In another example, HARQ A/N may be generated by DCI, ifconfigured/activated over a period of time or deactivated. In anexample, the WTRU may receive DCI (UCI). The WTRU may determine that theDCI(UCI) configures UCI reporting for a period longer than one subframe(or longer than one TTI), e.g., until it receives another DCI(UCI) thateither modify or deactivate the configured UCI reporting. In such case,the WTRU may generate and/or include HARQ A/N feedback for suchDCI(UCI), e.g., to report feedback for the reception of the DCI(UCI)itself. In one method, the WTRU may use the UCI reporting method(s)applicable prior to the reception of such DCI(UCI) for HARQ A/N reportof the concerned DCI(UCI). The WTRU may start using the newconfiguration in subframe n+x+1 when such DCI(UCI) is received insubframe n. For example, x may be equal to 4 and the WTRU may apply thenew configuration starting from the subframe following the transmissionof the HARQ A/N report for the concerned DCI(UCI). In one example, theWTRU may use the new configuration indicated in the DCI(UCI) itself forHARQ A/N reporting of the concerned DCI(UCI). The WTRU may start usingthe new configuration in subframe n+x when such DCI(UCI) is received insubframe n. For example, x may be equal to 4 and the WTRU may apply thenew configuration starting from the subframe of the transmission of theHARQ A/N report for the concerned DCI(UCI).

In an example, UCI not requested for an indicated type may besubdued/dropped. In an example, the WTRU may determine that it may nottransmit any UCI that is not part of a UCI request, when such request isreceived.

In another example, other methods may be used if UCI not part of any UCIrequest. In an example, the WTRU may determine that it may transmit anyUCI that is not part of a UCI request, when such request is received,using other methods, e.g., such as legacy methods. For example, when UCIscheduling indicates a transmission on PUCCH, the WTRU may routeremaining UCI to a PUSCH transmission (if such is available) accordingto legacy methods. For example, when UCI scheduling indicates atransmission on PUSCH, the WTRU may route remaining UCI to a PUCCHtransmission according to legacy methods, if both PUSCH and PUCCH aresimultaneous and possibly also for the same serving cell, only if theWTRU is configured for simultaneous PUSCH/PUCCH transmissions.

In another example, the WTRU may determine that it may not transmit anyUCI unless it receives a DCI(UCI) that includes a UCI request. In anexample, the WTRU may include UCI to any PUSCH transmission, e.g.,according to legacy methods even when it does not receive a DCI(UCI)that includes a DCI request.

In another example, a UCI type not part of the request may be eithersubdued/dropped or legacy transmission methods may be used. In anexample, the WTRU may determine that it may not transmit any UCI that isnot part of a UCI request, when such request is received.

In another example, a DCI(UCI) request may be for HARQ feedback only.For example, the WTRU may receive a DCI(UCI) that requests HARQ A/Nfeedback for specific HARQ processes and/or for specific serving cellsonly.

In another example, an alternative determination may be made. In someexamples, any of the information described herein for the UCI request orfor the UCI scheduling information may be implicitly derived by othermeans. For example, a specific RNTI may be assigned to indicate the typeof the DCI (e.g., DCI formats 0, 1, etc. compared with DCI formatDCI(UCI)), to indicate the type of UCI request, to indicate the type ofphysical channel (e.g., PUSCH vs PUCCH), to indicate the identity of thecell, or the like. Similarly, specific regions of the PDCCH Search Spaceor specific DCI Aggregation Levels or specific size for the CRC of theDCI may be assigned and may be used to determine similar information.

In another example, a semi-persistent allocation may be made. Schedulinginformation may be semi-persistently configured. In such case, theconfigured information may be used as the default schedulinginformation. In such case, the WTRU may receive a DCI(UCI) thatoverrides configured scheduling information for the applicable servingcell. In such case, the WTRU may refrain from performing anytransmission using a configured allocation when no UCI is generatedand/or available for transmission for the concerned time interval.Alternatively, for HARQ feedback the WTRU may report the value of theHARQ feedback following the last reception for the concerned processes,while for CSI feedback the WTRU may consider this as a periodicreporting configuration (e.g., if an aperiodic CSI configuration is alsopresent).

In another example, the selection of channel coding may be as a functionof dynamic scheduling information. The WTRU may select the appropriatechannel coding as a function of the UCI requested (e.g., channel codingmay be selected as per any of the methods described herein or usinglegacy methods for a different combination of at least one of HARQ A/N,periodic CSI, CQI/PMI and scheduling request) and/or the schedulingparameters for UCI (e.g., whether it is on PUCCH or on PUSCH (ifapplicable)).

In another example, the scheduling information for UCI may indicate aresource corresponding to a PUCCH transmission even if the WTRU isexpected to perform a transmission on PUSCH simultaneously, e.g., for agiven cell group (CG). In such case, the WTRU may perform thetransmission of the applicable UCI using the indicated resource ifsimultaneous PUCCH and PUSCH transmission is configured, e.g., for theconcerned CG. Otherwise, if the WTRU does not perform simultaneousPUCCH/PUSCH transmissions it may include the applicable UCI information(e.g., such as UCI requested in the dynamic scheduling information) in aPUSCH transmission according to legacy behavior. In an example, the WTRUmay include SR in the scheduled UCI transmission.

In some examples, the WTRU may be configured to transmit periodic CSIreports for more than one cell (multiple periodic CSI reports) in asingle subframe over PUCCH or PUSCH. The WTRU may also be configured totransmit HARQ-ACK and/or SR in the same subframe.

In some examples, a maximum payload may be configured in case oftransmission of HARQ-ACK and periodic CSI. The WTRU may be configuredwith a maximum payload for each PUCCH resource that can be used for thetransmission of HARQ-ACK, periodic CSI reports and/or SR in a subframe.The maximum payload may be expressed in terms of bits or in terms of amaximum code rate, in conjunction with the known number of availablecoded bits for the configured resource. Such maximum payload may bedependent on the combination of UCI being transmitted, e.g., whetherHARQ-ACK alone or a combination of HARQ-ACK, periodic CSI and SR istransmitted.

Alternatively or in addition, the WTRU may be configured with a maximumpayload of periodic CSI reports for each PUCCH resource which isapplicable independently of the number of HARQ-ACK and SR bits that aretransmitted in the resource. Such maximum payload of periodic CSIreports may be the same as the configured maximum payload of the PUCCHresource that is used in the subframe or that would be used for thetransmission of periodic CSI only in the subframe according to one ofthe solutions described herein. Alternatively, the maximum payload ofperiodic CSI reports in case a simultaneous transmission with HARQ-ACKand/or SR may be configured independently.

The WTRU may transmit a smaller number of periodic CSI reports than theconfigured number in a subframe where HARQ-ACK and/or SR are alsotransmitted in case the payload of periodic CSI reports would exceed aconfigured maximum payload of periodic CSI reports, or in case the totalpayload of HARQ-ACK, SR and periodic CSI reports would exceed aconfigured maximum payload for the PUCCH resource (or the total numberof UCI bits). The subset of periodic CSI reports that is transmitted maybe determined according to one of the solutions described herein.

In some examples, when transmission of HARQ-ACK collides withtransmission of multiple periodic CSI reports, the WTRU may transmit onone of the PUCCH resources configured for the transmission of multipleperiodic CSI according to a solution described herein. Alternatively,the WTRU may transmit on a periodic PUCCH resource indicated by downlinkcontrol information (i.e., a TPC field of SCell assignments/ARI).

The WTRU may be configured with more than one PUCCH resource for thetransmission of multiple periodic CSI reports in a subframe. In thiscase, the WTRU may determine the PUCCH resource according to at leastone of the following solutions.

In an example, the WTRU may select a PUCCH resource based on at leastone priority criterion. For example, the WTRU may select the resourceassociated with the serving cell whose periodic CSI report has thehighest priority in the subframe among all serving cells for which aperiodic CSI report is being transmitted in the subframe.

In another example, the WTRU may select a PUCCH resource based on thetotal payload of the periodic CSI reports to be transmitted in thesubframe, or the total payload of HARQ-ACK (if applicable), SR (ifapplicable) and periodic CSI reports. For example, the WTRU may select afirst PUCCH resource if the total payload does not exceed a threshold,and a second PUCCH resource otherwise. The threshold may correspond to,or be a function of, the maximum payload that can be supported for thefirst PUCCH resource, which may be less than the maximum payload thatcan be supported for the second PUCCH resource.

In a further example, the WTRU may select a PUCCH resource as a functionof the required transmission power based on the power control parametersand formulas associated with each resource. The transmission power maybe a function of at least one of resource-specific parameters,format-specific parameters, payload, number of resource blocks, coderate, power control adjustment, and/or path loss. For example, the WTRUmay select the resource that minimizes the required transmission power.In another example, the WTRU may select a first resource if the requiredtransmission power for this resource is below a threshold, and a secondresource otherwise, possibly only under the condition that the requiredtransmission power for the second resource is lower than the requiredtransmission power for the first resource plus a configured offset in dBterms. In the above, the required transmission power for each resourcemay be adjusted to correspond to a peak transmission power to accountfor possible differences in cubic metric (CM) and/or peak-to-averagepower ratio (PAPR) between different resources. The adjustment may be afunction of at least one property associated with the PUCCH resource,such as the PUCCH format or the number of resource blocks.

The WTRU may select a PUCCH resource based on whether HARQ-ACK and/or SRare also transmitted in the same subframe. The PUCCH resource to use incase HARQ-ACK and/or SR are also transmitted may be signaled fromdownlink control information, or configured by higher layers only.

In still another example, the WTRU may select a PUCCH resource based onthe timing of the subframe. For example, a first set and a second set ofsubframes may be associated with a first and a second PUCCH resource,respectively. Each set may be defined in terms of period and offsetrelative to the frame number and/or subframe number, or in terms of anindex representing the period and offset. For example, one set maycorrespond to subframes occurring with a period of 20 ms which includesubframe #3 of frame #0. The WTRU may select the first PUCCH resource ina subframe belonging to the first set only, and the second PUCCHresource in a subframe belonging to the second set only. For a subframebelonging to both sets, the WTRU may select the PUCCH resource based onat least one of the following. In an example, the WTRU may select thePUCCH resource based on a priority criterion. The priority may bepre-defined, or may be based on a property of the resource such as themaximum payload (or code rate) supported, the number of resource blocks,the starting resource block number or the format. For example, thepriority may be given to the PUCCH resource that can support the highestmaximum payload. In another example, the WTRU may select the PUCCHresource based on a solution already described elsewhere herein, such asbased on the total payload to be transmitted, the required transmissionpower and/or the priorities of associated serving cells for which areport is being transmitted.

In some examples, the WTRU may transmit a smaller number of periodic CSIreports than the configured number due to a power limitation. The WTRUmay first determine a maximum payload for periodic CSI reports and CRC(if applicable) or for the combination of periodic CSI reports, SR,HARQ-ACK feedback and CRC (if applicable) based on the maximum poweravailable for the transmission, the type of channel (PUCCH or PUSCH),the format in case of PUCCH, and other parameters and measurements(e.g., path loss) used for power control. The maximum payload may takeinto account the number of bits required for CRC addition, ifapplicable. Such maximum payload may be referred to as power-limitedpayload. In case the WTRU is configured with more than one PUCCHresource, the WTRU may first determine the PUCCH resource based on asolution described herein and then determine the power-limited payloadassociated with the resource. Alternatively, the WTRU may select thePUCCH resource which results in the highest possible power-limitedpayload.

The power-limited payload may be constrained to correspond to one of afinite set of allowed values for the maximum payload or to a parameterfrom which the maximum payload can be derived (such as a maximum numberof periodic reports or a maximum code rate). Such a set of allowedvalues may correspond the set of possible values that can be configuredas part of a PUCCH resource.

The maximum power available for the transmission may be determined usingexisting power scaling and allocation solutions when multiple cellsand/or cell groups are configured. In some solutions, the WTRU may beconfigured with a maximum power specific to a PUCCH transmissioncontaining periodic CSI. In this case the maximum power available forthe transmission may be the smallest value between this configuredmaximum power for periodic CSI and the maximum available power obtainedfrom existing solutions.

The maximum payload in case of PUCCH may be determined using arelationship between a number of information bits and a power offsetapplicable to the PUCCH format used for transmitting periodic CSIreports. The maximum payload in case of PUSCH may be determined from amaximum number of symbols (or ratio of symbols) that may be used for theencoding of the different types of CSI reports (RI, CQI and PMI).

When the number of bits required to transmit a set of periodic CSIreports according to configuration exceeds a maximum payload accordingto one of the solutions described herein, the WTRU may transmit a subsetof CSI reports based on a priority rule. The priority rule may be basedon legacy priority rules (i.e. type of report and serving cell index).The priority rule may also be based on at least one of the following:the time since the last transmission of a periodic report for a cell;the value of the CQI and/or RI. Possibly, only reports for which CQI/RIis above or below a configured threshold may be transmitted; and/or thechange of value of the CQI and/or RI since the last transmission of thecorresponding report for a cell (in an example, reports with highestchange of CQI and/or RI may be prioritized).

The WTRU may include a cell identity along with each set of CSI reportsfor a cell at least in case the priority cannot be known in advance bythe network or when only a subset of the reports are transmitted. TheWTRU may also transmit an indication, possibly encoded separately, thatonly a subset of the reports are transmitted due to power limitation.

In case the power-limited payload is lower than the number of bitsrequired for the transmission of only HARQ-ACK bits or HARQ-ACK and SRbits (plus CRC bits if applicable), the WTRU may not include anyperiodic CSI report in the transmission. In some solutions, the WTRU maynot include any periodic CSI in the transmission whenever thepower-limited payload is lower than what would be required for thetransmission of all periodic CSI reports, HARQ-ACK (if applicable), SR(if applicable) and CRC (if applicable) according to a configuration. Insuch a case, the WTRU may transmit only HARQ-ACK, SR and CRC, ifapplicable.

In some examples, the payload may be set to one of a finite set ofpossible value. For example, the WTRU may use padding (e.g. append thepayload with a number of “0” bits) such that the payload matches one ofa set of possible payload values that may be pre-defined or configuredby higher layers. This may facilitate blind detection of the payload bythe receiver at the network side. Such padding may occur after reductionof payload (for periodic CSI or other UCI) according to one of the abovesolutions. Possibly, padding may be performed only in case payloadreduction occurred due to a power limitation.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed:
 1. A wireless transmit receive unit (WTRU) comprising aprocessor and a memory, the processor and the memory configured to:receive a first downlink control information (DCI), the first DCIcomprising scheduling information for a first downlink transmission,wherein the first DCI comprises an indication that hybrid automaticrepeat request (HARQ) feedback for the first downlink transmission isnot expected in response to the first DCI; receive a second DCI, thesecond DCI comprising a request to transmit the HARQ feedback for thefirst downlink transmission; and transmit the HARQ feedback for thefirst downlink transmission scheduled by the first DCI based on therequest comprised in the second DCI.
 2. The WTRU of claim 1, wherein thefirst downlink transmissions comprise a first physical downlink sharedchannel (PDSCH) transmission.
 3. The WTRU of claim 1, wherein the secondDCI indicates scheduling information for transmission of the HARQfeedback for the first transmission scheduled by the first DCI.
 4. TheWTRU of claim 1, wherein the first DCI is received via a first physicaldownlink control channel (PDCCH) transmission, and the second DCI isreceived via a second PDCCH. The WTRU of claim 1, wherein the second DCIcomprises scheduling information for a second downlink transmission. 6.The WTRU of claim 5, wherein HARQ feedback for the second downlinktransmissions is transmitted with the HARQ feedback for the firstdownlink transmission.
 7. The WTRU of claim 1, wherein the indicationthat the HARQ feedback for the first transmission is not expected inresponse to the first DCI comprises a codepoint the first DCI being setto a specific value.
 8. The WTRU of claim 1, wherein the second DCI doesnot include scheduling information for a physical downlink sharedchannel (PDSCH) transmission.
 9. A method performed by a wirelesstransmit receive unit (WTRU), the method comprising: receiving a firstdownlink control information (DCI), the first DCI comprising schedulinginformation for a first downlink transmission, wherein the first DCIcomprises an indication that hybrid automatic repeat request (HARQ)feedback for the first downlink transmission is not expected in responseto the first DCI; receiving a second DCI, the second DCI comprising arequest to transmit the HARQ feedback for the first downlinktransmission; and transmitting the HARQ feedback for the first downlinktransmission scheduled by the first DCI based on the request comprisedin the second DCI.
 10. The method of claim 9, wherein the first downlinktransmissions comprise a first physical downlink shared channel (PDSCH)transmission.
 11. The method of claim 9, wherein the second DCIindicates scheduling information for transmission of the HARQ feedbackfor the first transmission scheduled by the first DCI.
 12. The method ofclaim 9, wherein the first DCI is received via a first physical downlinkcontrol channel (PDCCH) transmission, and the second DCI is received viaa second PDCCH.
 13. The method of claim 9, wherein the second DCIcomprises scheduling information for a second downlink transmission. 14.The method of claim 13, wherein HARQ feedback for the second downlinktransmissions is transmitted with the HARQ feedback for the firstdownlink transmission.
 15. The method of claim 9, wherein the indicationthat the HARQ feedback for the first transmission is not expected inresponse to the first DCI comprises a codepoint the first DCI being setto a specific value.
 16. The method of claim 9, wherein the second DCIdoes not include scheduling information for a physical downlink sharedchannel (PDSCH) transmission.
 17. A base station comprising a processorand a memory, the processor and the memory configured to: transmit afirst downlink control information (DCI), the first DCI comprisingscheduling information for a first downlink transmission, wherein thefirst DCI comprises an indication that hybrid automatic repeat request(HARQ) feedback for the first downlink transmission is not expected inresponse to the first DCI; transmit a second DCI, the second DCIcomprising a request to transmit the HARQ feedback for the firstdownlink transmission; and receive the HARQ feedback for the firstdownlink transmission scheduled by the first DCI based on the requestcomprised in the second DCI.